Ousama Ranking: Yuuki no Takarabako
English title: Ranking of Kings: The Treasure Chest of Courage
Japanese title: 王様ランキング 勇気の宝箱
Alternative titles: Ranking of Kings: Treasure Chest of Courage
Type: TV
Source: Web manga
Episodes: 10
Status: Finished Airing
Aired: Apr 14, 2023 to Jun 16, 2023
Broadcast: Fridays at 00:55 (JST)
Duration: 22 min per ep
Rating: PG-13 - Teens 13 or older
Studios: Wit Studio
Producers: Aniplex, Dentsu, Fuji TV, Kadokawa, Bandai Spirits
Genres: Adventure, Fantasy

"A treasure chest of unspoken courage is opened."

The special is described as a collection of shorts, showing past instances of courage and personal growth by the cast of Ousama Ranking. 

(Source: Ranking of Kings Wiki)