Peko and Mahiru are classmates in Class 77-B, as well as participants of the Killing School Trip.
In the first trial, Peko gets embarrassed when everyone starts talking about the possibility of laxatives in her food, and Mahiru puts the boys in their place by disapprovingly scolding them and defending Peko's privacy. She is the only student who makes an attempt to defend Peko's dignity. Peko seems thankful for this, before the topic of the trial is finally changed.
However, during chapter two, Mahiru plays to the whim of the second motive: Twilight Syndrome Murder Case. Playing the video game supplied by Monokuma, Koizumi learns about the real-life murder that had occurred at their school. She chooses to address what had happened with everyone involved, despite them all having lost their memories of the case. Mahiru invites Ibuki, Mikan, Hiyoko and Fuyuhiko. However, the former two decline, having other plans.
Peko overhears Mahiru inviting Hiyoko to discuss the murder, choosing to send each a fake message and arrange Mahiru's murder. Mahiru confronts Fuyuhiko Kuzuryuu (Peko's young master), angering the yakuza, who believes Mahiru to have a hand in the forgotten murder. Before Fuyuhiko could act, however, Peko bludgeons Mahiru with a metal bat. After urging her young master to escape, Peko rearranges Mahiru's body and left her in the beach house to be discovered by the other students later. Peko was later executed for her murder of Mahiru.
The two did not speak during Danganronpa 3: The End of Hope's Peak Academy.
Mahpeko is one of many ships were the individuals involved are victim and killer. Many shippers believe that since Peko killed for the safety of Fuyuhiko, she held no personal vendetta against Mahiru.
Mahiru's defense of Peko during the first trial was where many members of the fandom entered the ship. Likewise, they see Mahiru and Peko's similar protective personalities as qualities that make them worth shipping.
- Mahiru and Peko die sequentially, both in chapter two after one kills the other.
- This is one of several ships between a victim and their killer, with the others being; Leosaya, Chimondo, Yamaceles, Tsumionji, Band Aid, Nekodam, Komanami, Nishichino, Amamatsu, Shiromami, Tojoshi, Shinnaga, Iruhara, and Oumota.