Mitsuki Izumi

Mitsuki is energetic and optimistic, determined about his job as an idol as a result of his childhood dream to become one. He is like an older brother within IDOLiSH7 because he takes care of them, including being the cook for their meals.

He often acts as the straight man (or the Tsukkomi in Manzai routines) especially to his sub-unit members Yamato Nikaido and Nagi Rokuya. This sometimes extends to Momo as his fellow emcee, where both intentionally play it up for the audience.

Despite that, Mitsuki is actually self-conscious at heart and lacks a heavy amount of self-love. This is seen throughout the series where he finds himself aware of his low popularity within IDOLiSH7 and what some fans think of him, which was typically "annoying" for being the main speaker during their programs. In reality, his job is largely respected in the industry and he's received many compliments from different companies about his talent to which has brought him to tears on at least one occasion.

Mitsuki has amber-colored eyes and short peach-colored hair parted on his right. He is the shortest out of the main cast, and the shortest member in IDOLiSH7 at 5’5.

Mitsuki's parents own a bakery named Fonte Chocolat. He had a normal childhood and grew up with his younger brother Iori Izumi. Mitsuki has always aspired to become an idol ever since ZERO's visit to the bakery when he was young.

Prior to joining IDOLiSH7, he has failed countless of auditions as a result of his short stature. At some point Iori had intervened to suggest methods for him to succeed, including marketing himself to be cute; this resulted in a quarrel between the brothers as Mitsuki knew being cute would not be true to himself. It also developed a complex in him because his younger brother had always been "perfect" and did not have to worry about failing anything. They made up at some point, with Mitsuki initiating the apology.

Mitsuki was only able to join IDOLiSH7 as when Iori was scouted by Otoharu Takanashi, he accepted solely on the terms that Mitsuki will be allowed to audition with him as brothers and brought him to the Izumi household. Mitsuki thought they were being tricked, but after Otoharu had a proper meeting with their parents since Iori was still a minor, he agreed to it almost immediately. In Part 1 of the Main Story, Banri confirms that the initial reason for Mitsuki entering the group was because Iori would only accept the offer if Mitsuki was also accepted, but Otoharu says it was because he saw Mitsuki's talent, otherwise he would not have been accepted into IDOLiSH7 no matter the reason.

When some bullies tried to pick a fight with IDOLiSH7, Mitsuki told everyone to get back and faced them alone, getting himself injured in the process. Mitsuki is good at swimming. Mitsuki once saved Nagi and Riku from drowning in the ocean. Mitsuki often sings in the bathroom. One of Mitsuki's devilish traits is the way that he’s good at pretending to be someone younger. Mitsuki's role in the Ainana Academy drama is a female home economics teacher. Since IDOLiSH7 were still rookie idols then, the producers did the casting in a way that wouldn’t involve female stars. Mitsuki admits that he has a poor sense of direction. He's "the type who gets lost while brimming with self-confidence", because he’ll just keep going forward. Mitsuki claims to be bad with heights. Mitsuki does stretches to get taller. Iori gets told that he got all of their parents' good traits, whereas Mitsuki gets told that he resembles their granny in her youth. When the Izumi Brothers quarrel, Mitsuki is usually the one who will make amends first. When the Pythagoras Trio went to an amusement park together, Mitsuki tried using his youthful looks to get a student discount. Unfortunately, the information desk insisted that he present his student ID to get the discount. During the costume fitting for their unit song, where their costumes were hoodies, every time Mitsuki took down his hood, Nagi would pull it back up for him. Mitsuki took Nagi out for walks during midday for him to get used to the summer heat in Japan, in preparation for their outdoor live. When Tamaki learned that Mitsuki could make cakes, he’s been going over to Mitsuki's room whenever he’s hungry. Mitsuki also taught him that "those who don’t work don’t eat!", and in exchange for Mitsuki making him something, he’ll get Tamaki to wash a pair of his shoes. When the Pythagoras Trio went to an amusement park together, an old lady mistook them for TRIGGER.

Iori carries a superior air but has proper manners, although he possesses a poisonous tongue. He likes to have things well-planned and executed orderly, which is why if anything goes wrong, he cannot deal with it. he’s 17 while Mitsuki is 21. Iori has dark grey eyes and black hair with a fringe parted in the middle. In certain lighting, his hair appears to have a dark blue tinge to it.

Despite being the younger brother between the two, he is taller than Mitsuki Izumi by nine centimeters.