Shizuma is Reiji's best friend, and the person who understands him the most. Both of them, along with Asuma, are childhood friends and were raised together - however, Shizuma ended up being closer to Reiji than Asuma, in part due to Shizuma's telepath abilities as well as the class difference between them. Reiji is fully aware of Shizuma's respect for him, and appreciates the assistance and support that the other gives him. It can be said that without Shizuma's scheduling and constant background ministrations, Reiji might have already broken from the sheer pressure put on him by others' expectations. In the light novel, the two of them are stated to be perfect partners.
In the visual novel, Shizuma plays assistant to Reiji's many ideas and whims. However, Shizuma is greatly worried by Reiji pursuing his relationship with Nana, and the two come into conflict over this. It is only resolved by the impending race between Saisei and Honan. After Saisei loses, Shizuma slaps Reiji out of his self-blaming brooding tendencies, and the disagreement between them reaches its resolution. After Shizuma sees Nana prove her capabilities, he supports Reiji's decision to get together with her and in the epilogue he leave them alone for Reiji to do what he wants.
Reiji is the 'secret character' of the visual novel. Nana first meets him at the modeling agency where he finds her lost phone and returns it to her, expressing interest in the Melonko-chan charm on her phone strap. The two encounter each other either at the modeling agency or at official meets, and over time Reiji grows fond of her and goes out of his way to help her. He eventually confesses to her in July after Honan's loss to Kakyoin, but she turns him down due to both of them having more important responsibilities. Nevertheless, he remains a friend of her and invites her (as well as her team) to stay over in the Saisei campus for a three-day training camp.
Reiji doesn't stop talking to Nana nor helping her, calling her before matches to give her advice on her anxiousness and generally keeping her company. He becomes her counselor of sorts, and over time she falls for him in return. After Honan wins against Kakyoin and takes the EOS'17 crown, she rushes to find him alone and confesses to him before Galaxy Standard's concert for the closing ceremony.
In the epilogue, they are shown to have a successful long-distance relationship.