Yamada is the real man he's damn cool ! He has sharp eyes with things he's definitely not the dull type.
Yamada takes care of Akane really well and even more so after she caught the cold last time.
Yamada went with Akane when she met up with a girl from the game for the first time. They sit together in a cafe/bakery, this new girl - while Akane was away off the table - approached Yamada despite knowing that he's taken. Yamada politely yet bluntly told her to get off him and then he escaped to Akane lol .
He dealt with this matter on his own, he didn't let Akane be worried or experience jealousy.
I can tell you that only true man can do that, as jealousy is not a very comfortable feeling. I'm fed up with all the dramatic jealousy from other manga, and for me this manga is both realistic and mature in terms of feelings and behaviours.