August 20, 2026 · 12 min read · Episode guide · Episode 3 · Kagex Blog

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Demon Slayer Season 2 Episode 3 Review — Should Have Been

Anime hub: Demon Slayer · Mugen Train Arc

Contains spoilers for this episode.

Demon Slayer Season 2 Episode 3 Should Have Been promotional art
Official promotional art. © Koyoharu Gotouge / SHUEISHA / Aniplex / ufotable

Kagex rating: 9.1 / 10

Episode: Season 2 · Episode 3 — “Should Have Been”

Air date: October 24, 2021 · Runtime: ~24 minutes · Studio: ufotable

Demon Slayer Season 2 Episode 3 — “Should Have Been” — reviewed in full Kagex format. Hub: Demon Slayer: Kimetsu no Yaiba. Previous: Season 2 Episode 2 — Deep Sleep.

Hook

People search demon slayer episode 3 review when they want a straight answer: worth watching, what changes, and how it scores — without a random spoiler dump. “Should Have Been” is overall TV slot 29 (Mugen Train Arc). “Should Have Been” moves Tanjiro’s compassion test forward without resetting Nezuko’s stake. Tanjiro happily spends time with the family he once thought he lost. Yet this is only a dreamscape presented to him by E…

Spoiler-free top half; deep recap after the warning. Character links go to live guides where they exist.

Quick Information

  • Anime: Demon Slayer: Kimetsu no Yaiba
  • Season / Episode: Season 2, Episode 3 (overall #29)
  • English title: Should Have Been
  • Arc: Mugen Train Arc
  • Runtime: ~24 minutes
  • Studio: ufotable
  • Original air date: October 24, 2021
  • Kagex score: 9.1 / 10
  • Where to watch legally: Crunchyroll / Netflix (region-dependent)
  • Characters: Tanjiro Kamado, Nezuko Kamado
Demon Slayer official banner Season 2 Episode 3
Official banner art. © Koyoharu Gotouge / SHUEISHA / Aniplex / ufotable

Should You Watch It?

Worth it? Yes if you are on the Demon Slayer track in order. “Should Have Been” is load-bearing for Mugen Train Arc, not clip fodder. Score 9.1/10 reflects this hour’s craft and emotional turn.

Beginner-friendly? Only after earlier episodes. Open Episode 1 first.

Who bounces? Viewers who want zero training or dialogue — ufotable still spends minutes on breath forms, corps politics, and Tanjiro’s empathy.

Spoiler Warning

Spoilers for Season 2 Episode 3 (“Should Have Been”) follow. Stop above for a clean first watch. No later-arc spoilers beyond this episode’s end.

Story Recap

Ordinary Life

Tanjiro happily spends time with the family he once thought he lost.

Kagex beat note: “Should Have Been” uses ordinary life inside Mugen Train Arc. Tanjiro’s kindness is tested as corps rules, demon tricks, or hashira standards tighten. This recap stays inside Season 2 Episode 3 — no Infinity Castle spoilers.

Unexpected Incident

Yet this is only a dreamscape presented to him by Enmu (Lower One).

Kagex beat note: “Should Have Been” uses unexpected incident inside Mugen Train Arc. Tanjiro’s kindness is tested as corps rules, demon tricks, or hashira standards tighten. This recap stays inside Season 2 Episode 3 — no Infinity Castle spoilers.

Escalation

Enmu’s goal is to infiltrate the unconscious realms of the sleeping Tanjiro and friends to destroy their spiritual cores.

Kagex beat note: “Should Have Been” uses escalation inside Mugen Train Arc. Tanjiro’s kindness is tested as corps rules, demon tricks, or hashira standards tighten. This recap stays inside Season 2 Episode 3 — no Infinity Castle spoilers.

First Discovery

Can Tanjiro and his companions wake from their dreams before their spiritual cores are destroyed?

Kagex beat note: “Should Have Been” uses first discovery inside Mugen Train Arc. Tanjiro’s kindness is tested as corps rules, demon tricks, or hashira standards tighten. This recap stays inside Season 2 Episode 3 — no Infinity Castle spoilers.

Important Encounter

Tanjiro happily spends time with the family he once thought he lost. Yet this is only a dreamscape presented to him by Enmu (Lower One). Enmu’s goal is to infiltrate the unconscious realms of the sleeping Tanjiro and friends to destroy their spiritual cores. Can Tanjiro and his companions wake from their dreams before their spiritual cores are destroyed?

Kagex beat note: “Should Have Been” uses important encounter inside Mugen Train Arc. Tanjiro’s kindness is tested as corps rules, demon tricks, or hashira standards tighten. This recap stays inside Season 2 Episode 3 — no Infinity Castle spoilers.

Demon Slayer key visual Season 2 Episode 3
Official key visual. © Koyoharu Gotouge / SHUEISHA / Aniplex / ufotable

Story Analysis

ufotable’s Season 2 Episode 3 board prioritizes readable faces when breath styles stack VFX. “Should Have Been” (Mugen Train Arc) assumes you know why Nezuko’s box matters and why Tanjiro will not treat demons as faceless mobs — that moral friction is the series engine, not a mid-season lecture.

Kagex story score 8.7 for this hour only: Tanjiro happily spends time with the family he once thought he lost. Yet this is only a dreamscape presented to him by Enmu (Lower One). Enmu’s goal is to infiltrate the unconsciou… Compare with binge pace vs weekly 2019–2024 drops — the episode was designed as a chapter, not a clip montage.

Animation 9.0: water, flame, sound, and mist breathing all have distinct color scripts. When the episode goes quiet (training, travel, recovery), composition carries threat — cursed wisteria, crow reports, Corps rank badges.

ufotable’s Season 2 Episode 3 board prioritizes readable faces when breath styles stack VFX. “Should Have Been” (Mugen Train Arc) assumes you know why Nezuko’s box matters and why Tanjiro will not treat demons as faceless mobs — that moral friction is the series engine, not a mid-season lecture.

Kagex story score 8.7 for this hour only: Tanjiro happily spends time with the family he once thought he lost. Yet this is only a dreamscape presented to him by Enmu (Lower One). Enmu’s goal is to infiltrate the unconsciou… Compare with binge pace vs weekly 2019–2024 drops — the episode was designed as a chapter, not a clip montage.

Animation 9.0: water, flame, sound, and mist breathing all have distinct color scripts. When the episode goes quiet (training, travel, recovery), composition carries threat — cursed wisteria, crow reports, Corps rank badges.

ufotable’s Season 2 Episode 3 board prioritizes readable faces when breath styles stack VFX. “Should Have Been” (Mugen Train Arc) assumes you know why Nezuko’s box matters and why Tanjiro will not treat demons as faceless mobs — that moral friction is the series engine, not a mid-season lecture.

Kagex story score 8.7 for this hour only: Tanjiro happily spends time with the family he once thought he lost. Yet this is only a dreamscape presented to him by Enmu (Lower One). Enmu’s goal is to infiltrate the unconsciou… Compare with binge pace vs weekly 2019–2024 drops — the episode was designed as a chapter, not a clip montage.

Animation 9.0: water, flame, sound, and mist breathing all have distinct color scripts. When the episode goes quiet (training, travel, recovery), composition carries threat — cursed wisteria, crow reports, Corps rank badges.

Character Analysis

Tanjiro Kamado still leads — even when hashira or sound pillars dominate screen time, the episode tests whether his compassion survives corps doctrine. Nezuko remains the moral anchor in the box.

Supporting cast this hour should feel like people with jobs (corps guides, demons with backstory, civilians in Yoshiwara or the village). Kagex does not invent manga-only scenes to pad word count.

World Building

Demon Slayer Corps ranks, wisteria, Nichirin swords, and breathing styles advance in Season 2. “Should Have Been” adds Mugen Train Arc rules — how missions are assigned, what “twelve kizuki” pressure feels like on the ground, and how ufotable stages Taisho-era Japan without modern anachronism.

Animation

ufotable on TV: particle-heavy breath effects, 2D faces held long enough to read grief. Animation score 9.0 for this episode’s peaks vs dialogue coverage.

Music & Voice Acting

Score 9.0. “Akeboshi” (LiSA) opens Mugen Train TV. Movie cuts were re-stitched for weekly pacing; the flame motif is Rengoku’s hour. Japanese track is reference (Natsuki Hanae, Akari Kito, Hiro Shimono, Yoshitsugu Matsuoka).

Hidden Details

  • Crow messengers and Kasugai squares are logistics, not cute mascot filler.
  • Check Tanjiro’s nose reactions — smell is plot data in Kimetsu.
  • Episode title kanji often foreshadows the internal lesson (“Should Have Been”).
  • No manga chapter homework required for this page.

Best Moments

  • Tanjiro happily spends time with the family he once thought he lost.
  • Yet this is only a dreamscape presented to him by Enmu (Lower One).
  • Enmu’s goal is to infiltrate the unconscious realms of the sleeping Tanjiro and friends to destroy their spiritual cores.
  • Can Tanjiro and his companions wake from their dreams before their spiritual cores are destroyed?

Pros & Cons

Pros: Specific to “Should Have Been”; ufotable craft; emotional through-line for Tanjiro/Nezuko.

Cons: Requires sequential viewing; power-scaling debates start heavy in later seasons — not this page’s job to settle.

Final Verdict

Kagex overall: 9.1 / 10

  • Story: 8.7
  • Characters: 9.0
  • Animation: 9.0
  • Music: 9.0
  • Enjoyment: 8.7

“Should Have Been” moves Tanjiro’s compassion test forward without resetting Nezuko’s stake. Tanjiro happily spends time with the family he once thought he lost. Yet this is only a dreamscape presented to him by E…

What to Expect Next

Next: Season 2 Episode 4 (“Insult”). Sequential viewers should continue.

FAQ

Do I need Season 2 Episode 3?

Yes in order. Skipping “Should Have Been” leaves gaps Mugen Train Arc assumes filled.

English title?

“Should Have Been” (Fandom / streaming listings).

When did it air?

October 24, 2021 · ufotable · ~24 min.

Is this filler?

No. Demon Slayer’s slower hours are training, travel, or recovery with payoffs.

Overall episode number?

29 of 63 TV episodes across five seasons.

Character guides?

Demon Slayer characters.

Facts & spoilers hub?

Fact and Spoilers.

Keep exploring

Your turn

Did “Should Have Been” earn your continue button? Favorite frame or line?

Sources: Kimetsu no Yaiba Wiki (Fandom) synopses; ufotable / Aniplex credits.

Kagex extended note on “Should Have Been”: Tanjiro happily spends time with the family he once thought he lost. Yet this is only a dreamscape presented to him by Enmu (Lower One). Enmu’s goal is to infiltrate the unconscious realms of the sleeping Tanjiro and friends to destroy their spiritual cores. Can Tanjiro and his companions wake from … Demon Slayer succeeds when action serves Tanjiro’s refusal to dehumanize victims — even demons with tragic backstories. That ethic is tested again in Mugen Train Arc without undoing earlier choices.

Kagex extended note on “Should Have Been”: Tanjiro happily spends time with the family he once thought he lost. Yet this is only a dreamscape presented to him by Enmu (Lower One). Enmu’s goal is to infiltrate the unconscious realms of the sleeping Tanjiro and friends to destroy their spiritual cores. Can Tanjiro and his companions wake from … Demon Slayer succeeds when action serves Tanjiro’s refusal to dehumanize victims — even demons with tragic backstories. That ethic is tested again in Mugen Train Arc without undoing earlier choices.

Kagex extended note on “Should Have Been”: Tanjiro happily spends time with the family he once thought he lost. Yet this is only a dreamscape presented to him by Enmu (Lower One). Enmu’s goal is to infiltrate the unconscious realms of the sleeping Tanjiro and friends to destroy their spiritual cores. Can Tanjiro and his companions wake from … Demon Slayer succeeds when action serves Tanjiro’s refusal to dehumanize victims — even demons with tragic backstories. That ethic is tested again in Mugen Train Arc without undoing earlier choices.

Kagex extended note on “Should Have Been”: Tanjiro happily spends time with the family he once thought he lost. Yet this is only a dreamscape presented to him by Enmu (Lower One). Enmu’s goal is to infiltrate the unconscious realms of the sleeping Tanjiro and friends to destroy their spiritual cores. Can Tanjiro and his companions wake from … Demon Slayer succeeds when action serves Tanjiro’s refusal to dehumanize victims — even demons with tragic backstories. That ethic is tested again in Mugen Train Arc without undoing earlier choices.

Kagex extended note on “Should Have Been”: Tanjiro happily spends time with the family he once thought he lost. Yet this is only a dreamscape presented to him by Enmu (Lower One). Enmu’s goal is to infiltrate the unconscious realms of the sleeping Tanjiro and friends to destroy their spiritual cores. Can Tanjiro and his companions wake from … Demon Slayer succeeds when action serves Tanjiro’s refusal to dehumanize victims — even demons with tragic backstories. That ethic is tested again in Mugen Train Arc without undoing earlier choices.

Kagex extended note on “Should Have Been”: Tanjiro happily spends time with the family he once thought he lost. Yet this is only a dreamscape presented to him by Enmu (Lower One). Enmu’s goal is to infiltrate the unconscious realms of the sleeping Tanjiro and friends to destroy their spiritual cores. Can Tanjiro and his companions wake from … Demon Slayer succeeds when action serves Tanjiro’s refusal to dehumanize victims — even demons with tragic backstories. That ethic is tested again in Mugen Train Arc without undoing earlier choices.

Kagex extended note on “Should Have Been”: Tanjiro happily spends time with the family he once thought he lost. Yet this is only a dreamscape presented to him by Enmu (Lower One). Enmu’s goal is to infiltrate the unconscious realms of the sleeping Tanjiro and friends to destroy their spiritual cores. Can Tanjiro and his companions wake from … Demon Slayer succeeds when action serves Tanjiro’s refusal to dehumanize victims — even demons with tragic backstories. That ethic is tested again in Mugen Train Arc without undoing earlier choices.

Kagex extended note on “Should Have Been”: Tanjiro happily spends time with the family he once thought he lost. Yet this is only a dreamscape presented to him by Enmu (Lower One). Enmu’s goal is to infiltrate the unconscious realms of the sleeping Tanjiro and friends to destroy their spiritual cores. Can Tanjiro and his companions wake from … Demon Slayer succeeds when action serves Tanjiro’s refusal to dehumanize victims — even demons with tragic backstories. That ethic is tested again in Mugen Train Arc without undoing earlier choices.

Kagex extended note on “Should Have Been”: Tanjiro happily spends time with the family he once thought he lost. Yet this is only a dreamscape presented to him by Enmu (Lower One). Enmu’s goal is to infiltrate the unconscious realms of the sleeping Tanjiro and friends to destroy their spiritual cores. Can Tanjiro and his companions wake from … Demon Slayer succeeds when action serves Tanjiro’s refusal to dehumanize victims — even demons with tragic backstories. That ethic is tested again in Mugen Train Arc without undoing earlier choices.

Kagex extended note on “Should Have Been”: Tanjiro happily spends time with the family he once thought he lost. Yet this is only a dreamscape presented to him by Enmu (Lower One). Enmu’s goal is to infiltrate the unconscious realms of the sleeping Tanjiro and friends to destroy their spiritual cores. Can Tanjiro and his companions wake from … Demon Slayer succeeds when action serves Tanjiro’s refusal to dehumanize victims — even demons with tragic backstories. That ethic is tested again in Mugen Train Arc without undoing earlier choices.

Our reaction

Spoiler-aware take after the recap — how the episode felt to watch.

9.1/10

“Should Have Been” moves Tanjiro’s compassion test forward without resetting Nezuko’s stake. Tanjiro happily spends time with the family he once thought he lost. Yet this is only a dreamscape presented to him by E…

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