Hikari then thinks Kei is joking and that pisses of Kei. She doesn’t realize he likes her till like, volume 9-10 of the manga. Which most likely won’t make it into the anime.

Yahiro is in love with Akira, but Akira hates him after she lost a friend because of him – he didn’t like other people talking to her and a commoner girl was using Akira, and Yahiro found out what she wassoing but Akira took it the wrong way and hated Yahiro since then. That’s why he hates commoners (Hikari).

Tadashi doesn’t play a big role in the romance till a bit more into the series…