Not that these stories usually make much sense, but this one makes even less sense than usual. Why wouldn't Lemon just explain the circumstances? Especially now, after all this time has passed.
My frustration with that behavior completely faded by the end—the story did a good job explaining why the characters acted the way they did. But I won’t lie, it was definitely frustrating at the beginning.
I’d argue that being in love with her own sister and then sleeping with her sister’s ex-girlfriend to be spiteful—something that was obviously hurtful—is a huge red flag and creepy. That alone is reason enough to avoid her.
It’s been so long since I read the beginning, but I’m pretty sure they weren’t just making out. That makes the whole thing even weirder. Our MC should run, this is way too creepy.
This chapter had more romance than the rest of the comic, but once again, it just highlights what a terrible person Yami is. And I have no doubt that Hikari will forgive everything—she's practically written as a saint.