Hakuōki 薄桜鬼 〜新選組奇譚〜
Souji Okita (沖田総司, Okita Souji) is one of the main characters in Hakuouki Shinsengumi Kitan.
Angered by Kondou's death, and his own weakening condition, he kills off an entire group of men that were planning to assassinate Hijikata.
Since he was already weak, his life force was sapped away by using his Rasetsu powers, and as a result his body turned to dust.
@ Souji Okita 沖田総司
helper thanks nightxx