ACUTE then ReACT

A song about a triangle love of a man (Kaito) and two women (Miku and Luka). Though they have been good friends, the two women get entangled with the man and are in love with him, who has a pang of regret. Presumably, Miku becomes engaged to him as there is a ring on her finger. One night when Miku phones Luka, Luka is with Kaito. Miku feels to be betrayed and anger for having a promise broken. She goes up to Kaito while he is fondling Luka with a knife in her hand and brings him close to her arms in front of Luka. But, Miku resisted not to stab Kaito, but she stabbed herself by her neck. She gave them a mysterious smile which had unsure meaning.

Miku wasn't dead, she was taken by hospital and there, she met Len. Miku knew that Kaito and Luka were living happily together and feeling irritated about it. Len was always there, accompanying her. They got so close , hence it made Rin feeling angry and jealous with Miku. The relationship between Miku, Len and Rin continued in the sequel of this song, ReAct.