Michael and Hoichael

Michael and Hoichael are two kids who are troublemakers in the backstreets of Water 7. They idolize Franky, and even dress like him and use his motto as their own: "Mm, super!!" They also idolize Paulie.

Water 7 Arc
They were originally suspected by Tilestone and Peeply Lulu to be the assassins who were after Iceburg. In the manga, their only appearance after that is to show Zoro the way back to Galley-La headquarters when Garp arrives. In the anime, they come back for an episode of Post-Enies Lobby filler.

Post-Enies Lobby Arc
When Garp arrives, a scene is added with them where they attempt to mug Zoro when he is trying to return to the Galley-La house to warn the others. But Zoro beats them up and has them show him the way back. In the manga, he shows up with them, and no explanation is given for how they met and they are never seen again.

In a filler episode, the two reappear as members of Aunt's "family"; while not related by blood, they consider each other siblings, and Aunt their mother. They appear before Zoro and force him to join their family over his objections. Zoro leaves after helping them defeat some loan collectors, saying that he considers his crew his family.