You can really see it in how Eijun mirrors Miyuki when he tries to lead Koushuu. During arguably the most personally pivotal game of his baseball career so far, when he has to prove he can lead the team without Miyuki, his instinct is to fall back on everything Miyuki taught him.
when you think about it, eijun did try to come up with some nicknames for miyuki and though a lot of them are negative, if you look more into it and take into account jp culture, it is Extremely romantic/shows their closeness. this is why he’s come up with a ton of nicknames