Here is the full list of all 21 Jigoku Kisetsukan: Sense of the Seasons achievements.
Complete the game with ??? at Hell difficulty
Complete a story without killing anyone
Complete the game with ???
Complete a story without dying
Complete the game with six characters
Complete the story
Complete the game with five characters
Complete the game with Fumin
Complete the game with Mizuiro
Complete a story at Hard difficulty
Complete the game with Nibiiro
Complete a story at Normal difficulty
Complete the game with Eiko
Complete a story at Easy difficulty
Complete the game with Tenshi
Complete a story at Hell difficulty
Complete the fourth level
Complete the third level
Complete the second level
Complete the first level
Start the Game