Love Come Manga ni Haitte Shimatta node, Oshi no Make Heroine wo Zenryoku de Shiawase ni Suru

I was sent into the world of a popular rom-com manga, and into the body of the male lead's best friend. Now I have the chance to make my dream come true: to make Sei-chan, the losing girl of the manga, happy!

"I can give you all the happiness you deserve, so please go out with me."

"Wait a minute! Are you serious?"

(Source: Newtype Web, translated)