Yamiochi Last Boss Reijou no Osananajimi ni Tensei Shita. Ore ga Shindara Bad End Kakutei nanode Saikyou ni Natta kedo, Mou Yamiochi "Yandere-ka" Shitemasen ka?
Alternative title: I Reincarnated as the Villainess' Childhood Friend Who Falls Into Darkness. If I Die, It's a Guaranteed Bad End, so I Became the Strongest... but Hasn't She Already Fallen Into Darkness [And Turned Yandere]?, Yami-ochi Rasu Bosu Reijou No Osananajimi ni Tensei Shita. Ore ga Shindara Bad End Kakutei na node Saikyou ni Natta kedo, Mou Yami-ochi "Yandere-ka" Shitemasen ka?, 闇堕ちラスボス令嬢の幼馴染に転生した。俺が死んだらバッドエンド確定なので最強になったけど、もう闇堕ち【ヤンデレ化】してませんか？
Story Overview
I, Arcus Fort, am a reincarnated soul. Because of this, I recognize that the world I'm now in is the setting of the popular otome game Celestia Kingdom from my previous life. At first, I assumed she was just some random side character, but it turns out she's actually the childhood friend of the terrifying final boss. If my memories from my past life are accurate, doesn't that mean my eventual death will lead to a dark fate?! Somehow, I've managed to become the strongest without falling into the typical bad ending. But there's something off about her... "Hey, why aren't you looking at me...?"