As much as I don’t like Kido, I think his character is important for Rio’s whole character development. And I don’t think that Rio still have feelings for Kido, it’s just that Kido is his only friend and the only one who actually believe in him (and his talent). Kido on the other hand, I think he’s not fully happy in his married life, not because of his wife or his kid but because he’s not fully honest about his self. Kuzumi on the other hand, he’s fully aware of his feelings for Rio and he’s ready to face everything at this point. I think he pretty much understands Rio’s character as well.
As much as I don’t like Kido, I think his character is important for Rio’s whole character development. And I don’t think that Rio still have feelings for Kido, it’s just that Kido is his only friend and the only one who actually believe in him (and his talent). Kido on the other hand, I think he’s not fully happy in his married life, not because of his wife or his kid but because he’s not fully honest about his self. Kuzumi on the other hand, he’s fully aware of his feelings for Rio and he’s ready to face everything at this point. I think he pretty much understands Rio’s character as well.