Shokubutsu Monster Musume Nikki: Seijo Datta Watashi ga Uragirareta Hate ni Alraune ni Tensei shiteshimatta node, Korekara wa Kougousei wo Shinagara Shizuka ni Shokubutsu Life wo Sugoshimasu

Who knew that even a stationary plant could be surprisingly capable?!

Our protagonist is a saint—or was, until she was betrayed by one of her fellow saint apprentices as well as her fiancé, a hero.
In her final moments, she recalls her previous life, when she was just a normal Japanese high school girl, but that doesn't help the fact that she's being eaten alive by a massive plant monster.

And yet, by a stroke of luck, she doesn't die for good, but instead reincarnates as said plant monster. With the upper half of a human and the lower half of a plant, she must now spend her life as an Alraune.

And so, she tries to live the peaceful life of a plant, photosynthesizing all day! Welcome to the diary of a plant girl who just wants some peace and quiet, but something always gets in her way!

(Source: Kadokawa, translated)