Seihi

He is the son of the owner of a ramen shop. Nao starts working there after getting into an accident on the road when he hits her with his bike(it was actually her fault because she was not concentrating on the traffic lights). His father was sick so he had to take care of the shop all alone. During the accident Nao broke bowls which were specially made bowls worth 13,000,000 yen (They later find out that they had been tricked since no bowls could be that expensive) given to them by their most rich and special customer, Nakatsugawa-Sama. They go to apologize to him and when they tell him, he says that the person who made them was a person he loved very dearly. At the same time Landlady-san, the owner of the apartment Hisashi and Nao live in, comes in and gives him new, handmade bowls. They find out that the 'Boyfriend' that she keeps mentioning is Nakatsugawa-sama and the bowls now get replaced by the bowls that she newly made for him. She was working for them in debt for the bowls and now she didn't need to so she leaves. Later she realizes that she can't work anywhere else so she comes back. When Seihi is at work, he has a really furious face but outside, he is really sweet and appears to have feelings for Nao. But in chapter 53 of Good Morning Call, he realizes that it is just that he loves her as a sister. (Source: Wikipedia)