Usaida is a graduate from Morinomiya Academy and is currently working as a staff for the Morinomiya daycare centre. He is the main person to care for Midori in the daycare and is often seen with her on his back.
Usaida is a tall man with shoulder-length strawberry blonde hair which is usually parted in the center and pulled into a short ponytail. He has dark, half-lidded eyes which make him look sleepy.
He usually wears an apron and a long-sleeved top, and wears a small ring in each of his ears. He is usually seen either sleeping or with a crooked grin on his face.
While seen as lazy for sleeping all the time, Usaida is helpful and cares greatly for the children, even rushing down to the daycare from home when he was seriously ill with fever because he was afraid Midori was in some sort of trouble. The children in the daycare room appear to trust him well and play with him affectionately, even though Kirin has called him "bad" with no redeeming qualities when asked for his good points.
He appears to be very observant and calm in any situation, sensing Ryuuichi's feelings easily and providing timely advice and help. For instance, when Taka is asked about his father by the rest of the children, he helped an anxious Ryuuichi who was not able to handle the situation by pointing out to Taka that "not all families are alike" and that Taka still has his brother.
He can be very blunt though, and often complains about his meagre pay and openly calling the chairwoman "a cheapskate", or commenting on the naivety of the children. He is also shown to be cunning and intelligent in getting favors from others such as luring Inui in with a fishing rod and a photograph of Yukari to make him keep watch over Kotarou.
Usaida's father was an elite businessman who expected much of him while he was growing up. This makes Usaida study very hard. Eventually, his father went bankrupt and decided to become a farmer, telling Usaida to live his life the way he chooses. Suddenly adrift, Usaida had nothing to do and spent an entire year aimless and sleeping everyday. Following that, the chairwoman's son, Morinomiya Youichi, scouted him for a job working at the daycare, even making him go along with the then pregnant Yukari to parenting classes in place of her husband, who was away on another archaeological dig. It can be interpreted that Usaida at one point may have been attracted to Yukari due to her youthful and beautiful appearance. Usaida felt indebted to the kindness of Morinomiya Youichi, who advised him to also "find his dream" while working at the daycare room and studying for his childcare license. To date, Usaida is secretive about his family and does not reveal it to others.
One day, Yukari who was on her way to pick Midori up, suspected that Usaida might have a girlfriend due to him being sleepier than usual. She dragged a surprised Ryuuichi and Kotarou along to spy on him as she is also curious about "the type that he likes". Ryuuichi followed as he is also worried about Usaida's health and him having "narcolepsy". Eventually, they spotted Usaida entering a shop and in close contact with an unknown woman. They tailed them back to an apartment, presumably her house, and both Yukari and Ryuuichi are shocked that he might be having an affair with a married woman after encountering the fierce, bald man who lived in there. After several misunderstandings, it was revealed that Usaida was actually tutoring him as he wanted to be a better husband and father to his unborn child. Afterwards, Ryuuichi apologized for his rudeness of tailing him, but Usaida thanked and revealed his past family circumstances. Ryuuichi asked if he had found his dream, to which Usaida replies as "a secret".
- The "Usa" in his last name contains the kanji for "rabbit".
- He is very good at sewing, making stuffed toys and costumes for the children.
- The reason for his sleepiness is because he stays awake at night tutoring his neighbour.
- Along with Ryuuichi and Hayato, he disguises himself as a girl under the name "Usako" to trick Kumatsuka Satoru.
- He is rarely shown with his hair down, only in chapter 24 and in chapter 33 when he is sick.
- According to chapter 25, he is 23 years old.
- He likes girls who wears glasses.