Nation’s Opening Festival is Tempest showing off: Takt’s orchestra, Shuna and Shion’s duet, Vesta and Gabil’s potion flex, Luminous trading culture for a gift of power. Then Gard admits the coins are dying, and someone is trying to starve the party.
Previous: Season 3 Episode 19 — Festival Eve · Hub: That Time I Got Reincarnated as a Slime
Hook
Nation’s Opening Festival is Tempest showing off: Takt’s orchestra, Shuna and Shion’s duet, Vesta and Gabil’s potion flex, Luminous trading culture for a gift of power. Then Gard admits the coins are dying, and someone is trying to starve the party.
This page is the sequential stop after Episode 19 — not a random recap dump. Scores below are for this 24 minutes only.
Quick Information
- Anime: That Time I Got Reincarnated as a Slime
- Season / Episode: Season 3, Episode 20 (overall #68)
- English title: Nation’s Opening Festival
- Japanese episode title: 開国祭
- Runtime: ~24 minutes
- Studio: 8bit
- Original air date: August 30, 2024
- Kagex score: 8.6 / 10
- Where to watch legally: Crunchyroll (region-dependent)
Should You Watch It?
Watch it for the concert and the money-plot turn. If you skip, you miss Luminous’s cultural-exchange deal and why Elmesia’s gold later matters. Low combat. High “is this a country or a con.” Class S finding out their teacher is the king is the comedy.
Beginner-friendly? No as a start point. Watch from Season 1 Episode 1. This installment assumes you already know Tempest’s core cast — Rimuru at minimum.
Bottom line: sequential viewers should not skip “Nation’s Opening Festival.” Fight-only watchers may feel the talkier stretches; nation-building fans will not.
Spoiler Warning
Spoilers for Season 3 Episode 20 (“Nation’s Opening Festival”) follow. Stop above for a clean first watch. This page does not spoil later episodes.
Story Recap
Class S meets the boss
Class S learns Rimuru is the monster king. Tiss is too shocked to function. Hinata arrives; Rimuru explains her history and warns them not to insult her. She agrees to watch the kids because they smell like Shizu. Luminous is coming too — she was invited. The school-trip joke is now a diplomatic incident waiting to happen, held together by a Saint who looks like a strict homeroom teacher.
The show
Takt, a young halfling, leads an orchestra. Shuna and Shion duet. Vesta and Gabil demo potions and stun Jeff. This is the festival as proof of civilization: art, science, not just an arena. Rimuru is not begging for recognition. He is putting on a fair that would look expensive in Ingrassia. That is the point of a founding.
Luminous wants culture
After the concert, Luminous asks for cultural exchange, gifts Rimuru a new power, and gets her researchers permission to do business in Tempest. They eat. Rimuru talks with Hinata and Yuuki about the week so far. Vampire god as arts patron is funnier than another treaty table. It is also Lubelius planting labs in the monster capital, which is alliance as infection in both directions — healthy, for now.
The coins go wrong
Gard says they are low on money and the coins they have are useless. Someone is sabotaging the festival economically. Rimuru sketches a fix, then they decide to enjoy the night anyway because the martial arts tournament is tomorrow. That delay is character: he will not let a market attack cancel the show. It is also how you know the Rossos did not need a dragon. They needed a mint.
Tomorrow, fists
Art today, brackets tomorrow, money underneath. The opening festival succeeds as culture and starts failing as a cash register. Rimuru has a plan he has not executed. Dwargon and Elmesia have not dumped gold yet. The audience is supposed to feel the creak.
Story Analysis
Tensura arguing “we are a country” with a concert is sincere to the point of corn, and I am fine with that. The potion demo is the science fair version. The coin crisis is the knife. Comedy is Tiss blue-screening. Emotion is Hinata plus Class S as Shizu’s leftover classroom. Pacing is showcase then ledger.
World-building is cultural exchange as a Demon Lord treaty, researchers as a fifth column you invited, and currency attacks as war. After holy swords, a mint is a scarier weapon. Luminous gifting power for a concert is the Octagram doing patronage.
Character Analysis
Rimuru is impresario and soon-to-be emergency treasurer. Class S and Tiss are the audience who thought this was a field trip. Hinata is the Shizu-shaped chaperone. Takt is the night’s artist. Shuna and Shion are the duet. Vesta, Gabil, Jeff — the science beat. Luminous is the patron. Yuuki is still at the table. Gard is the one who has to say the word bankrupt. The kids’ shock is the joke that keeps Rimuru’s double life honest.
World Building
Festivals are GDP. Orchestras and potion industries are state capacity. Currency can be attacked independently of armies. Lubelius researchers in Tempest are a two-way tech leak by consent. A Demon Lord can gift power as concert payment. Students from Ingrassia walking a monster capital is the coexistence pitch in miniature. Tomorrow’s tournament is already advertised as the next proof of life.
Nothing here is later-arc homework. If a name or rule is only teased, it stays a tease.
Animation
Concert lighting, duet, potion effects, then a grim ledger scene. Spend on the performance; keep the money talk still and ugly. Class S reaction faces are free comedy. A culture-week look, not an action week.
Kagex animation score for this episode: 8.4 / 10 — peaks vs average cuts, not a sakuga clip ranking.
Music and Voice Acting
Score 8.8. 8bit’s TV mix leans on Elements Garden sting + silence. Japanese track is the reference for Rimuru’s dual register (cute slime vs office-brain). Dub timing varies by season; don’t wait on it to judge the episode.
Hidden Details
- Useless coins are the Rosso/Muese plot from Episode 24 starting in the cashbox.
- Hinata chaperoning Class S is Shizu’s classroom reconstituting under a Saint.
- Luminous trading a power for culture is alliance as fandom, which is very her.
Best Moments
- Tiss learning her coworker runs the country.
- Shuna and Shion actually pulling off a duet.
- Gard admitting the money is already dead.
Pros & Cons
Pros: Specific to “Nation’s Opening Festival” —
The festival’s best argument — art and science — plus the first clear economic attack. Watch the concert. Stay for the coins. The tournament is next; the ledger is the real opponent.
Cons: Requires earlier episodes. Viewers who only want climax fights may call the political / logistics scenes slow even when they are load-bearing.
Final Verdict
Kagex overall: 8.6 / 10 —
The festival’s best argument — art and science — plus the first clear economic attack. Watch the concert. Stay for the coins. The tournament is next; the ledger is the real opponent.
- Story: 8.6
- Characters: 8.6
- Animation: 8.4
- Music: 8.8
- Enjoyment: 8.7
The duet made me grin. The coin scene made me sit forward. This is the episode that proves the festival is not only padding — someone is trying to starve it.
What to Expect Next
Brackets, an Elite Four, Lion Mask, and Gobta cheating at sport in the most Gobta way.
Next: Season 3 Episode 21 — The Martial Arts Tournament. Watch legally on Crunchyroll.
FAQ
Do I need to watch Season 3 Episode 20?
Yes if you are watching the TV series in order. Skipping “Nation’s Opening Festival” leaves a hole later episodes assume you have.
What is the Japanese title?
開国祭 — Crunchyroll English title is “Nation’s Opening Festival.”
When did it air?
August 30, 2024 in Japan. ~24 minutes. Studio 8bit.
Is this Season 3 filler?
No. Tensura’s “quiet” hours are usually nation, diplomacy, or setup — not recap filler.
Where does this sit in the overall count?
Overall TV episode 68 of the main series (S1–S3 are 72; Season 4 continues from 73).
Should I watch Slime Diaries first?
No. Diaries is optional comedy. This review is the main TV track.
Where are character guides?
Tensura characters — Rimuru, Veldora, Milim, and the Tempest officers.
Where are facts / spoilers for the franchise?
Fact and Spoilers on the hub. This episode page stays inside Episode 20.
Keep exploring
- Tensura anime hub
- Season 1 review
- Overall review
- Previous: Season 3 Episode 19 — Festival Eve
- Next: Season 3 Episode 21 — The Martial Arts Tournament
- Characters
- Fact and Spoilers
Your turn
Was “Nation’s Opening Festival” a continue episode or a skip-risk for you? Favorite beat? Who should get the next character page?
Sources: Crunchyroll episode titles; Wikipedia list of Tensura episodes; official Tensura anime site.
