An undefeated Japanese champion who trains in isolation in the harsh Japanese mountains.
While you likely mean the feature film, there is also a notable titled In Full Bloom directed by Maegan Houang. This surrealist short tells the story of an older Vietnamese hoarder whose life is literally consumed by a black hole that opens in her home. In Full Bloom (Short 2019) - IMDb In Full Bloom(2019)
The film has been praised for its artistic ambition but received mixed reviews regarding its pacing: An undefeated Japanese champion who trains in isolation