Kitakado Tomohisa and Korekuni Ryuji are childhood friends. They first met at a party where they both sneaked out and played in the snow and built snowmen and snow bunnies. Later on, both of them were enrolled in Bambi school, and by luck, they were placed in the same unit.
Both share a close bond. There are rare times when they take jobs separately. But if it happens, they are worried and think about the other's wellbeing. Though their concern for the other sometimes becomes a burden to their bond as they tend to hide their problems and deal with them on their own, much to the displeasure of their partner. In his SSR [BIRTHDAY PARTY] and the Season 2, ep. 4 Tomohisa rather hid his negative feelings from Ryuji which caused a rift between the two. It becomes apparent that Ryuji wants his partner to be more open with him when it is about his worries since he also wants to help him solve those problems.
In the issue of 2D☆STAR vol.3 Ryuji said if he was a girl it would be impossible to mingle with Tomohisa as their values are too different. But he didn't think anyone else would be his partner except for Tomohisa. The latter would choose Ryuji as his boyfriend if he was a woman. This shows that despite their difference in thinking and personalities they think of each other as irreplaceable.
Even though both boys grew up in wealthy families their individual understanding of the common life differs greatly. Ryuji often has to correct or teach Tomohisa simple things. While the latter enjoys learning new information and is greatful to his childhood friend, Ryuji sometimes lets out a sigh at the lack of his partner's personal awareness. Ryuji's opinion matters a lot to Tomohisa. So he tends to cook the dish that was complimented by his partner multiple times to please Ryuji.
Moreover, Tomohisa likes to tease Ryuji about his occasional dishonesty which makes the latter blush in embarrassment. Nevertheless, both feel the most comfortable around each other's presence.