Kei is the worst written character in this manga and I hope this is the start of either fixing her character or pushing her to the sideline. I have nothing against shoujo ai/Yuri characters in manga so long as they are done right and not rushed. From Chapter 2 - 4 Kei was read as the typical "jealous childhood friend who shows her affection by bullying the MMC". But after Chapter 5, where she some how fell in love with FMC after knowing here for a few hours, she just gives off a "misandrist lesbian who hits the MMC out of jealousy".
Edit:
Oh and let's not forget that one of the main reasons the MMC is held up in his room is because of Kei.