Fairy Tail: The Utterly Ordinary Doomsday Superman

[Overpowered protagonist + feel-good story + heavily altered plot + multiple heroines] Aier transmigrates. Though he has no idea why he has become Natsu's older brother, he wakes to find Natsu crying in his arms, so he accepts the little guy as his younger brother. He had planned to ride his little brother's coattails, but instead awakens a Superman System. However, after the System is attacked, it is reduced to a wreck. It can only turn him into Doomsday Superman before self-destructing and disappearing. Now all he can do is live a disciplined, hardworking life and grow stronger day by day. Natsu: Discipline? Getting sunshine every day really is pretty disciplined! Lucy: Hard work?! You call running to the sunniest spot every day to bask in the sun hard work?! Aier: Then how else did I get stronger? It was all thanks to my discipline and hard work! After all, I'm really just an ordinary guy! Everyone from Fairy Tail: Shut up! Acnologia the Black Dragon: Ordinary? Would an ordinary guy suddenly fly up here and beat me to a pulp?!!! (The protagonist's abilities are a bit too overpowered, so the plot will change a lot. The people closest to him will get a huge power boost, but that only applies to Natsu!)