Between Red & White [White Lotus-San

I got reincarnation to another world. What should i do?

Another Sinopsis:
After Yuna confessed her feelings to her best friend and was rejected, she went to the beach with an alcoholic drink in her hand. As she was about to leave, a wave suddenly pulled her into the sea and she drowned. When Yuna opened her eyes, she found herself inside the book she had last read. And she was just a side character who would die in the end! What should she do?