Draco in Leather Pants: Arata Tasaki, despite his actions, is popular in the Japanese side of the fandom most likely due to his rugged looks and his attitude.
Yuudai slowly warming up to Taisei after Taisei repeatedly tries to befriend him with unfaltering enthusiasm, especially considering how awkward and blushy Yuudai is around him. After the brothers and these two have an excessive drinking night together, Yuudai loses his shirt and has to go home with Taisei's t-shirt on.
Jerkass Woobie: Yuudai openly hates most people and acts incredibly abrasive to his coworkers, but most fans are willing to forgive him since he has trust issues courtesy of his abusive ex-boyfriend.
Nightmare Fuel: Theface Taisei makes in the last panel of this strip is kinda creepy - even if we find out that it was just leading up to the first appearance of "business mode."
On a more serious note, most scenes involving Yuudai and Arata in the same room tend to be particularly anxiety-inducing. Fridge Horror, thy name is Arata Tasaki.