Sachiko's husband and Hikaru's father. Early on, Masato seemed to be unsympathetic to what Sachiko was going through in while he was at work. This was half true; Masato's high level position in the company he worked for provided a good income for his family, but took hours of strenuous work, leaving him little time to talk to her. The other half of the coin was that Masato was embarrassed by Hikaru's behavior and upset by his diagnosis. He and Sachiko separated temporarily after a fight about Hikaru's behavior and Masato's refusal to face the issue. Without her around to make sure he was taking care of himself, he collapsed from overwork in the first volume of the series. This event prompted him to rethink his priorities and he settled instead on trying to become a better father to Hikaru. Masato is demoted in the third volume by a vicious superior and sent to a factory far away where no one lasts more than a few days, if a week. With no work to do, Masato completes a series of proposals for products and ideas to improve the lives of disabled people and find them work within the company. These proposals get him promoted in volume four and he sets about setting up a mushroom factory in the factory where he was sent with the intention of having it staffed by disabled persons, perhaps even Hikaru someday.