Here is the full list of all 8 Otoko Cross: Pretty Boys Mahjong Solitaire achievements.
Cleared all stages of character Morgan.
Cleared all stages of character Haru.
Cleared all stages of character Quincy.
Cleared all stages of character Jules.
Cleared One Stage.
Played first round of Mahjong Solitaire!
Cleared all stages of character Kyun.
Cleared all stages of all five characters.