Boku Ga Boku Wo Yameru Hi (Media Works Bunko) [Light Novel]

[Machine Translation] "If you would rather die, why don't you become me? Junki Tatei, despairing of living, was on the verge of committing suicide when he saved her, and since then she has been living as "Kensuke Takagi," a secret between the two of them that no one knows about. It was a secret between them that no one knew about until two years later when a murder occurred... Tatei, who is in a tight spot after being accused of murder as Takagi, tracks down the whereabouts of the missing Takagi. The man who gave him his name may be a murderer. In the midst of his struggle, Tatei eventually discovers a sealed tragedy, a spectacular past as a boy, and the shocking plans of the present Takagi.

「死ぬくらいなら、僕にならない?」生きることに絶望した立井潤貴は、自殺寸前で彼に救われ、それ以来“高木健介”として生きるように。それは誰も知らない、二人だけの秘密だった。2年後、ある殺人事件が起きるまでは...。高木として殺人容疑をかけられ窮地に追い込まれた立井は、失踪した高木の行方を追う。自分に名前をくれた人は、殺人鬼かもしれない―。葛藤のなか立井はやがて、封印された悲劇、少年時代の壮絶な過去、そして現在の高木の驚愕の計画に辿り着く。