Even though this is all fun and games, this doujin really portrays Honoka quite well. People often mistake Honoka for this ever-so-cheerful annoying filler character (even though she's practically the leader) but in truth, she's the one who had it the hardest. If you've read her School Idol Diary, then you know that she often belittles herself. It's not like she wanted to play the martyr though. It's that she herself doesn't accept who she is. She tries her hardest to make everyone smile, to push everyone forward. But in truth, she's hurting herself the most and in time, overworks herself until she breaks her limit. The only one she could rely on was Umi, and even SHE didn't know what to do with Honoka at times.
That's why Nico's probably one of the few people who could get Honoka to the right track. To stop her from doing everything alone, from abusing herself. Nico may be an idiot, but she's the idiot who could speak their heart out to her friends without holding back. And that's just what Honoka needs.
The slap was hella funny tho.