Ruki, wrote a sad song called "reila". In the song he sings about a girl named reila, who he loves, but she committed suicide. I have found out that, reila, was ruki's old girlfriend years back who committed suicide herself. That could be the reason ruki's eyes look glassy and tear-filled when he sings "reila" in the pv and at the concerts. Who ever she was, reila must have really been loved by ruki.