|Series:||AKB48 Murder Mystery|
|First Appearance:||File 1|
|Last Appearance:||File 5 (cameo)|
|Number of Episode|
|4 (File 1, 2, 5 and Testimony File)|
- "She's having more and more fans! But she always looks depressed. She's Nagao Mariya from Team 4!"
- ―Mayuyu introduces Mariyagi[src]
Mariyagi was with the rest of Team 4 after Sashiko found their fellow member, Rena, in the hallway, beaten to death. After Acchan inspects the scene, she (along with the rest of AKB48) were shocked at Acchan's conclusion that the culprit is among the members present.
- "It wasn’t me! The N from the dying message isn’t me! That is, depending on the angle, couldn’t it look like a Z? It’s definitely a Z! The member who has initials of Z… Huh? There aren’t any! Then… it’s not a name… Maybe Z is that thing…"
- ―Nagao Mariya's Testimonial[src]