Nozomu Igarashi is a student at Four Star Academy, attending the male division. He is a member of the male idol unit M4 and is the second known male idol student in the franchise. His catchphrase describes him as an orthodox prince who is surprisingly hot-blooded and straightforward. He has a calm and mature personality and is kind and refreshing toward his juniors. Despite his composed exterior, he possesses a surprisingly passionate and hot-blooded side. He is a hard worker and a good student with excellent grades. He is also able to read the room well. He has a humble disposition, once remarking that M4 still had a long way to go when the protagonist Yume Nijino failed to recognize them. Nozomu is an avid reader who enjoys books from various genres, particularly mystery novels, as he likes piecing together hints and reasoning through the clues.

His specialties include studying and sports in general, and he is presumed to be M4's main dancer, as his major is dance. He has a fondness for world heritage sites and gratin dishes. Within the story, Nozomu serves as a supporting character. He appears in the Yotsuboshi Film Festival production of The Little Fairy Story as the prince who partners with Yume in the lead role. Along with the rest of M4, he performs in various events, including Halloween and Christmas episodes, and the group holds their first live performance on a music program in episode 43. Nozomu often interacts with his fellow M4 members, particularly teasing Subaru Yuki, and shows leadership qualities during group training sessions. Over the course of the series, he and the other members of M4 continue to grow as idols. After M4's dissolution, he advances to Asia alongside Kanata Kira.