Because his only knowledge of the world comes from what he's learned from the internet and TV, his understanding of things is a little off. He was born into the Suou branch family. He's a persevering, hard worker, but he has an especially sharp tongue toward those close to him. He speaks in the Kyoto dialect, and he behaves as if he's more mature than he actually is. He has a sharp, clear voice, and his performances are delicate and beautiful.
Kohaku is a young, petite boy of average build. He has short pink hair cut slightly above his shoulders with his bangs swept to the side and lavender eyes. He's been stated to have a cute face. 
On stage with Crazy:B, he wears a houndstooth-patterned jacket with yellow, black and purple accents. He has a bee-shaped brooch pinned on the left side of the jacket. Underneath his jacket, Kohaku wears a black shirt with a white honeycomb logo. He wears black pants with white and yellow stripes and a white honeycomb pattern running down on the side of his pants, fastened by a golden chain around his waist. He wears black loafers with the toe, sole, heel and metal strap colored yellow. For accessories, Kohaku wears a stinger-like necklace, two bracelets on his left hand, and one ring on his left thumb.
On stage with Double Face, Kohaku wears a big dark green top piece, cut off just above his waist. It has short sleeves, and is decorated with several golden buttons and a muted yellow sheriff star adorned by two similarly-colored strings. The top piece is colored red on the inside. Underneath his top piece, Kohaku appears to wear a light grey shirt and long black gloves, with his shirt neatly tucked into his pants. Kohaku's pants also consist out of two pieces; on top he wears dark green shorts, secured by a black and red belt and two straps on each side. Under his shorts, he wears grey pants and black thigh-high boots.
Thanks to his unique upbringing and family, Kohaku stands out as a rather old-fashioned individual. He speaks with a Kyoto dialect, often making obscure, old school-esque references. He is also surprisingly mature for his age, well-mannered, and eloquent.
Despite his cute looks and polite demeanor, however, Kohaku has a very sharp tongue. A no-nonsense type of person, he never sugarcoats his words, and isn't above threatening others (usually being genuine) if he's teased too much or finds himself irritated by the person in question. He also has a cynical worldview, often remarking on the evil in the world and his rather unfavorable self-image.
Although he doesn't show it easily, Kohaku does care deeply about his friends, and he's willing to go to extreme lengths in order to ensure their safety and well-being. Whenever he gets especially emotionally involved, his more childish side slips out, which HiMERU describes as being like a childish temper tantrum. 
The ou character (桜) in Kohaku's surname, Oukawa, is the same ou character in Tsukasa Suou's surname. The word for "cherry blossom" used in Kohaku's title uses the same ou character (桜) in his surname as well.
- Kohaku stands as the shortest member of Crazy:B.
- Presumably, his age makes him the youngest member of Crazy:B.
- He is the youngest and shortest member of Double Face.
- Kohaku usually stays at his Reimei dorm room with Jun. It's currently unclear whether he spends more time at his Reimei dorm or his new Ensemble Square dorm room after the !! Main Story.
- According to a 4gamer interview with Akira, Kohaku's character archetype is "a prisoner" (こはくが囚人で).
- Kohaku is currently one of the only characters who are active in two official units that aren't shuffle units or temporary units at the same time besides the Eden members.
- He and Aira Shiratori were previously online friends before they met in person during the events of the Ensemble Stars!! main story. He calls Aira by his online handle, which embarrasses Aira.
- Prior to February 2021, Kohaku was listed as being part of Class 1-S in Reimei Academy on the official website. This was officially confirmed within an in-app announcement to be a mistake because he has never attended school (as was specified in some in-game stories) and is just allowed to stay in the Reimei dorms.
- Among the events of the "Ensemble Stars!!" era, Kohaku made a new appearance with Madara Mikejima as part of Double Face. It was established as a unit under New Dimension on July 16, 2020.
- He's never attended any schools before.
- According to his statement in Antique Legend , Kohaku didn't grow up in Kyoto, despite speaking in a regional Kyoto dialect. The reason for his dialect is that his family used to live there a very long time ago and, out of tradition, still insists on members of the family speaking in the regional dialect even though they've long since moved to the region where ES is located.
- His sweets preferences mirror Tsukasa's, although Kohaku prefers Japanese sweets while Tsukasa prefers western ones. Both of these tastes originate from a shared family tradition of having an afternoon snack time, although Kohaku personally considers this tradition to be pointless. 
- The casual outfit he wears in the summer was chosen for him by a fashion shop employee, because prior to that he had only worn kimonos and has very little knowledge of modern-looking clothes.
- He had a sheltered upbringing, mostly learning about the outside world through media and the internet. He frequently references being previously locked up for a long time in a zashikirou, a form of solitary confinement from the Edo period for those considered "harmful to the public". He often expresses enjoyment of his newfound freedom.
Voice Actor Comment
"I share a lot of similarities with Oukawa Kohaku-kun; one of them is the Kyoto dialect. I can utilize the dialect of my hometown when voicing him, so I felt very happy when I got this role! I would be very happy if his personal charms, such as his use of the pronoun "washi" (used mostly by elderly people) and his unique laugh etc. can be conveyed to everyone. Kohaku-kun is slightly lacking in knowledge of the ways of the world, but please take care of him!" 
|Crazy:B||Rinne Amagi • HiMERU • Kohaku Oukawa • Niki Shiina
(Madara Mikejima • Kohaku Oukawa)