紅恋歌 (Kou Renka)

Background
Kurenai Renka is an original song by Mazo-P featuring KAITO. It's a rock song, telling the story of a shinobi(KAITO) who has fallen in love with the woman whom he was ordered to kill. Failing to carry out his mission, he runs away with the woman but later kills himself, as he couldn't live after betraying his master.

The song is featured on Mazo-P's album, Gessouya.