Kenji when he met
Marina. Him and her are good friends. He meets
Shou when he was with Marina, in front of her house, after their day's work. Like Marina, he feels sorry for him that the girl he loves is in love with another boy.
He supports Marina who is trying to cheer him up but, secretly in love with Marina, he is afraid that "something more" will develop between them. When Shou starts spending less time with Marina, and seems to be a bit depressed about it, he is sure that there was more than friendship between them.
(spoiler hidden)