Maybe 'Doubt'. I don't think the mask is cute tho
idk if you seen this one but there ya go
http://www.mangago.zone/read-manga/the_moon_is_beautiful_tonight_but_first_die/
Just some recs
http://www.mangago.zone/read-manga/jinrou_game/
more romance like >///< http://www.mangago.zone/read-manga/shinrei_tantei_yakumo/
Really good http://www.mangago.zone/read-manga/tenkuu_shinpan/
http://www.mangago.zone/read-manga/prison_lab/
http://www.mangago.zone/read-manga/kami_sama_ki_sama_o_koroshitai/
close but not quite it ㅠㅠ i will for sure read it !!
maybe ? i remember seeing it only once before
im looking for this manga with a guy that kills with a really cute bunny mask.... ive only seen it once !! or pls recommend some horror mangas/manhwa