Tomohisa Kitakado Edit
Kazuna and Tomohisa met in Bambi and became close friends. They worked a reporting job together and went to different locations together often for filming.
At some point after their debut, their relationship became strained because of Kazuna growing jealous and insecure over Tomohisa's talents and natural light he had. Despite this, he still liked and admired his friend and the complicated emotions caused him to withdraw and sometimes clash with him. Kazune doesn't like when the two are compared, often feeling inferior despite his group mates trying to tell him how great he really is.
Tomohisa would try to reach out to him but even after taking a step forward, Kazuna would withdraw once more.
Their relationship starts to rekindle in the anime after Kazuna finally lets out his building frustrations and insecurities to Tomohisa, revealing how badly he's felt this whole time on top of trying to find his mother but feeling like he couldn't with Tomohisa standing in his way. After hearing him out, Tomohisa reassures and comforts Kazuna, telling him he has his own bright like and that together with B-PROJECT, his mother will find him again. After this, their relationship slowly starts to mend.
MooNs look up to Kazuna, calling him Leader despite him asking not to, though he does accept it a little reluctantly. They often try to cheer him up when he's feeling down and are quick to reassure him that he's better than what he makes himself out to be and usually are quick to take his side in things and stand by his decisions.
Kazuna greatly appreciates their efforts and support, and always looks out for them and tries to do what he thinks is best for them even if he causes him to clash a little with other groups. Sometimes their antics can get a little too much for him but he still cares about them all.
Ryuji Korekuni Edit
Though not exactly close, Kazuna and Ryuji get along well despite Kazuna's rocky relationship with Tomohisa, who is Ryuji's partner. The two sometimes clash over ideas but make up quickly after. Ryuji has shown to be concerned and a little bothered over Kazuna and Tomohisa's problems but tries not to interfere with it though can be a little blunt when asking him what's wrong.
Kento Aizome Edit
Kento watched over Kazuna once on a job after Tsubasa expressed concerns over him and Tomohisa. Kazuna grew flustered when Kento pointed out that Kazuna liked Tomohisa, despite how he tries to pass it off.
Yuta Ashu Edit
Yuta has expresses some concern for Kazuna when he thinks he's been crying or is bother by something, once taking Ryuji's Chupa Chups to try to cheer him up. He teases him sometimes, like when he pretended to try to feed him a strawberry and making Kazune flustered when he at ate it himself to show it was a joke.