Kore wa Nidome de Saigo no Hatsukoi

Kotone Amamiya dies after catching her best friend, Airi Sasaki, in bed with her boyfriend. She wakes up back in high school and realizes she's been given a second chance at life. Determined to make the most of it, Kotone cuts the toxic Airi out of her life and pursues the life she's always wanted to live, including another chance with her first love, Minato Naruse. Will Kotone find her new happily ever after, or will Airi's devious schemes be too much to overcome?

(Source: Webtoon Entertainment)