Kanojo to Kareshi no Akarui Mirai

A man named Ichirou, unremarkable and ordinary, is in a happy relationship with his stunning and affectionate girlfriend, Yukika. Despite his contentment, he becomes troubled after encountering someone who claims Yukika had a promiscuous past. While he tries to focus on their present, he becomes consumed by disturbing thoughts about her history. To investigate, he uses a virtual reality time machine that accurately reconstructs past events, leading him to take a morally questionable action.