Transferred to another world, but I'm saving the world of an Otome game!?

Because of his little sister, high school student Tarou (Placeholder) is transferred to an otome game as the heroine. The more he tries to avoid the handsome love interests, the further he advances into their love routes!

In the end, will he be able to return to his original world?!
And will he be able to protect his chastity?!

(Source: Shonen Gangan, translated)

Note: Chapter count ncludes the original two-part story as prologue, plus five volume bonus chapters, four extras chapters, four "Ore Hero" Arasuji Manga Gekijou chapters, and a Shonen Gangan 30th Anniversary bonus manga.