I love how this sort of rides the line between a cute, 'wholesome' tone (particularly due to the art) and a twisted, ominous one. Throughout the story, I was expecting a turn into absolute insanity and potential violence, but the story doesn't quite take that road. As constraining as their codependency is, the characters show self-awareness and a semblance of remorse. They're certainly not good for each other, but they're not plain yandere. They feel like real people with real issues.
Even at the most dramatic points in the story, the art isn't especially dark or serious. Haa looks cute - not scary or tragic - when she lashes out. Ryou's smile looks genuine and not yandere-ish when she reveals that she was purposefully inciting Haa's jealousy. Ryou watches blankly as Haa apologizes and invites her friends, and when the next page doesn't show her face it builds some tension, but then you see that she's just cutely pouting. The 'heaviest' parts, visually, are some large panels with a lot of negative space that place our main pair off-center, which further emphasize how they have built a prison for themselves. Well, those panels along with the few isolated, totally black panels.
I've really liked the few stories available from this author. Hope to see more from them.