Yamamoto has always admired Gokudera.
Be it little things such as his way of being graceful when fighting, but then he thinks – because how can you be graceful when throwing bombs? He doesn't know, but he likes how Gokudera can pull it off. Even as he mentions it to him while training, he can't help but admire the way Gokudera yells at him, telling him to focus before throwing another dynamite in his direction, then tucking his head in the crook of his shoulder, trying to hide the small smile spreading on his lips.
–
Gokudera has always, although grudgingly admits, admired Yamamoto.
The way he fought was one thing, sometimes acting like the aloof idiot he was, other times serious. Like when he fought seriously with Squalo, defeating him, but in the end caring about his health condition more than his own; he couldn't help but admire that. But now he wonders why he admires Yamamoto at all, as Yamamoto mentions that he thought Gokudera was graceful while fighting – obviously not taking Gokudera's training methods seriously, he thinks. His response being a brisk yell and a dynamite to the face.
He denies any and all accusations that he was, in fact, smiling.
–
Tsuna admires both Yamamoto and Gokudera.
He likes how they are both good friends – even though Gokudera denies it adamantly. He admires their consistency of pulling through for one another, helping. If only he could be that strong, he thinks. If only he could...But then Reborn kicks him and tells him to focus because he accidentally said that aloud. He rubs his cheek and sighs, continuing to look at Gokudera's and Yamamoto's own training session and – wait! Was Gokudera smiling?! Tsuna breaks out into a small smile of his own.
He admires both Yamamoto's and Gokudera's own admiration for one another.