Hiroyasu Ueda is the owner and head baker of a small bakery called Chiroru. He is a man in his late thirties, though he has a noticeably youthful appearance, often described as a baby face, which makes him look much younger than his actual age. He is tall with short, dark hair and gray eyes.

Ueda has a kind, gentle, and patient personality. He is a deeply sincere and loyal individual who values emotional authenticity and the power of memory. Despite carrying a significant melancholy from a past loss, he remains a compassionate person who is capable of loving deeply. He can be somewhat reserved and shy, but his fundamental nature is welcoming and warm.

His primary motivation stems from a profound personal tragedy involving a persocom, the humanoid computers that populate his world. When he first opened his bakery, he purchased a persocom to help him with his accounting, a skill he admits is a weakness. Over time, he fell in love with this persocom, named her Yumi, and eventually married her. Their happiness ended when the persocom developed a hard disk error that caused her memories to slowly degrade, similar to dementia in a human. She would forget conversations moments after they happened and would wander away. Ueda could not bring himself to have her repaired, as he feared that the process of transferring her data to a new hard drive would erase her personality and memories, essentially destroying the person he loved. He continued to care for her, treasuring the rare moments when fragments of her memory returned. The tragic conclusion came when, during a walk, Ueda was lost in thought and stepped into the path of an oncoming truck. In a final, inexplicable moment of clarity, his persocom pushed him to safety, sacrificing herself. Her final word to him was Hello, the default greeting of a newly activated persocom with no memories.

This event shaped Uedas role in the story. He serves as a poignant example of the complex and heartbreaking relationships that can form between humans and persocoms. He is one of the few, and possibly the first, known person to have legally married a persocom. This backstory also becomes the central obstacle in his relationship with Yumi Omura, a young woman who came to work at his bakery. The two fell in love, but when Yumi discovered that Ueda had been married to a persocom and that the persocom shared her name, she felt she could never compete with the memory of the other Yumi and left him. Ueda remained patient and did not pursue her aggressively, respecting her feelings. It is only through the intervention of the series protagonists, who help Yumi understand that Ueda truly loves her for herself and not as a replacement, that the two are able to reconcile and resume their relationship. This romance represents Uedas personal growth, showing his ability to open his heart again after devastating loss.

Ueda has a cameo appearance in another work, Kobato, where he again appears as the owner of a bakery, demonstrating his established character archetype across different stories. As a baker, his notable ability is his skill in creating pastries and cakes. He is excellent with recipes but is consistently portrayed as being very bad at mathematics and bookkeeping, which is the original reason he purchased a persocom for assistance.