|Anime debut||The Season You Were In|
|Japanese voice actor||Hidehiko Kaneko|
|English voice actor||Blake Shepard|
He was first introduced in The Season You Were In when a younger Misae attempts to go home with him. They are, however, interrupted by Katsuki, and Igarashi, assuming that Katsuki is Misae's boyfriend, decides to leave the two alone. This causes Misae to get mad at Katsuki.
The next day, Misae stumbles into Katsuki again. Katsuki figures out that Misae likes Igarashi and asks if she wishes to get married to him. Misae refuses, saying that he can't manipulate other people's feelings. Later that day, Misae and Katsuki encounter Igarashi again, where he refers to Katsuki as Misae's boyfriend.
Igarashi appears again later in the episode and continues to think that Katsuki is Misae's boyfriend. Katsuki says that he isn't and explains that Misae likes someone else. Igarashi then tells Katsuki that he knows that Misae likes him, but he already has a girlfriend. He then asks him to tell Misae the truth while hurting her as little as possible.
Katsuki then tries to explain the situation to Misae by saying that he likes a girl, but that girl likes another boy, but that other boy already has a girlfriend. Misae, at first, does not realize that he is talking about her, but then figures it out when she sees Igarashi walking by with his girlfriend.
Misae quickly gets over Igarashi as her relationship with Katsuki begins to develop.