Haimiya Mio

키오세 학교에는 모두가 두려워하는 한 상급생 여학생이 있다.

중학생: 야 쿠로세, 오늘도 나 대신 보건실 당번 좀 해줘. 보건 위원회 정식 멤버답게 정말 믿음직스럽다니까?

그 중학생의 친구들이 낄낄거리며 웃는다.

쿠로세: 아하하... 그런 것 같네... (속마음: 언젠가 반드시 되갚아 줄 거야!..)

그때 갑자기 누군가의 목소리가 들려온다...

하이미야: 야! 아침부터 왜 이렇게 시끄러워? 내 손에 얼굴 다 뭉개지기 싫으면 당장 꺼져, 이 새끼들아!

중학생: 죄... 죄송합니다! 중학생들은 서둘러 도망친다.

그녀는 바로 악명 높은 하이미야였다. 보이는 그대로, 정말 무시무시한 분위기다! 아마도...

쿠로세: (속마음: 하이미야는 보건실에 자주 있어... 땡땡이 치는 건가? 그래서... 보건 위원으로서 가끔 그녀와 이야기를 나누곤 해. 응, 대충 그런 식이지... 하지만...)

하이미야: 와, 쿠로세잖아. 너 또 청소 시켰어?

쿠로세: (속마음: 왠지... 나한테만 다정하게 대해줘...) 응... 그게... 음...

하이미야: 왜 그래?.. 부끄러워?

. Kurose is not afraid of him
Almost everyone in school is afraid or stays away from Mio because of her appearance (piercing, wolf-cut, sharp eyes) + her rough way of speaking in Kansai dialect.
Kurose was one of the few people who wasn't afraid and still spoke normally to her. That's what made Mio feel comfortable and special around him.
2. They often meet in the UKS room
Kurose is a member of the health committee, so she often goes to the infirmary. Mio also often hangs out and sleeps there.
From their daily interactions in the same place, Mio began to notice Kurose and felt that he was different from the others.
3. He has a crush on Kurose
This is the most important thing.
After they started getting closer, Mio fell in love with Kurose. That's why she became gentle, caring, and only showed her sweet side to him.
To other people, he remains "fierce", because that is his way of protecting himself and he doesn't want to be close to just anyone.
4. There is a bit of mystery about his past
In several chapters, it was mentioned that Mio seemed to have difficulty making friends and may have experienced something in the past that made her who she is now.
Kurose became the first person to successfully “enter” his small world.
Short conclusion:
Mio is only friendly to Kurose because she likes him, and he's someone who isn't afraid of her "scary face." That's what makes Mio feel special and comfortable enough to show her true, soft side.