Raira Trio

The Raira Trio is a group made up of Mikado Ryuugamine, Masaomi Kida, and Anri Sonohara.

Relationship
Initially termed a "love triangle," the trio has a deep friendship that started at the beginning of their first year at Raira Academy. Masaomi regularly hits on Anri and teases Mikado, Mikado relies on Masaomi as he becomes familiar with the big city and is silently in love with Anri, and Anri struggles with her feelings of affection for the boys and values them deeply for pulling her out of the walls she had set up around her emotions. All three go to great lengths and rely on all their resources to protect each other.

Mika Harima Arc
Mikado enrolls at Raira Academy at the request of his childhood friend, Masaomi. On the first day, Anri volunteers to be the female class representative of class 1-A, and noticing Anri looking in his direction, Mikado volunteers to be her partner. After school, Mikado and Masaomi are walking through town when they notice Anri being cornered and bullied by the ganguro girls. With some physical encouragement from Izaya Orihara, Mikado steps in to help her.

While walking home from school the next day, Mikado and Masaomi spot Anri asking Seiji Yagiri about their missing classmate, Mika Harima. They walk with Anri and ask her about her friend and her middle school life. As the three begin to open up to each other and spend more time together, they find their friendship growing.

Saika Arc
Mikado and Masaomi are alarmed when Anri is attacked by the slasher and visit her in the hospital. Masaomi begins to spend less time with his friends after the incident.

Yellow Scarves Arc
Unbeknownst to his two friends, Masaomi returns to lead the Yellow Scarves and uses them to find the slasher suspected to be hiding within the Dollars. Izaya reveals the name of the Dollars' leader, causing feelings of doubt and betrayal in Masaomi. Anri has been worried about Masaomi and discovers his secret as leader of the Yellow Scarves, becoming a target for the gang in the process. Mikado temporarily disbands the Dollars, as he fears for his members' safety, and Anri deals with the predatory teacher Takashi Nasujima and his jealous ex-girlfriend, Haruna Niekawa, while being hunted by Yellow Scarves members. The relationship between the three becomes strained as they struggle to hide their individual secrets, but ultimately their secrets come out when they come face-to-face in the Yellow Scarves' headquarters.

After recovering in Raira General Hospital from his fight with the remnants of the Blue Squares, Masaomi and Saki Mikajima leave Ikebukuro together without a word.

Hollywood Arc
Mikado and Anri start their second year of high school alone, but they are by this time famous within their school for their tight-knit friendship, and many classmates believe they are dating. Though they both have feelings for each other, they deny their feelings in an effort to keep everything as it was for Masaomi's return to the city. While struggling to deal with Masaomi's absence, a new member called Bacura joins the chat room, giving Mikado reassurance that Masaomi is doing fine.

On their first day, first-year student Aoba Kuronuma asks them for a tour of Ikebukuro, and they consult Erika Karisawa and Walker Yumasaki for help. The day of their tour, the pair and Aoba end up being pulled into a high-speed chase involving the van gang, motorcycle gang Toramaru, motorcycle cops, and Celty Sturluson. The van gang drops them off away from the fighting, but Mikado and Anri, feeling it their duty to help their friends, return to the scene.

A short while after the event, Celty and Shinra Kishitani host a hotpot party and invite Mikado and Anri.