Akuyaku Reijou wa Scenario wo Shiranai: Otome Game no Sekai de Shinjitsu no Koi wo Sagashimasu!

Marie has had memories of her past life since she was five years old. Upon entering the academy, she finally realizes that the world she's living in is the setting of an otome game her little sister loved! However, she barely remembers the characters or the story. Since she knows nothing, she decides to take it easy and aim for a wonderful romance. But soon, she finds herself attracting the affection of the very love interests who are supposed to be vying for the protagonist...!?

(Source: Kodansha, translated)