Nabigatoria ni Koi
While I love this author's works, this is nothe case here. The more Kei was developed as a character the less sense and less likable he became for me. He explains later on he regards people as disposable (while critiquing his parents for essentially having his same characteristics) and he says he likes to charm people to pass the time. Given how Yuri opposed him from the very beginning, why waste his time with Yuri? Not to mention at one point his persistance just turned creepy. One thing that bugged quite a bit actually was when the very young sisters ask to go to the sightseeing trip and Yuri (who knows how and where it is) says no, only to be undermined by Kei, who is not going to be capable of taking responsibility for them. And that's just what happens. Yuri is distracted by Kei's antics and so he loses one of his sisters. The thing luckily ends up well, but it just adds to the irresponsibility of Kei's character that makes me just not like him as a potential partner for anyone
Omega Shunki