So obviously this is a runaway story between a sheltered kid and a suspicious man. Suppose you find it interesting to make an escape from lousy daily life where nobody gets you, jumping from train to train, and waking up next to a kind stranger in different hotels. In that case, this story is perfect to indulge in your fantasy because it ticks all the boxes in a pleasant way. A relationship between an adult and a minor has always been a grey area so all I can say is that the author managed to portray Hirose as a gentle and warm person which compensatesfor his relationship with Hajime.

But if you are a person whose sense of logic and reasoning can sometimes be a bit jarring (like me), then there are still some parts of the plot that don't sit right. It just swirls the tone of the story to a pinky, jolly dimension where none of the problems would have existed in the first place.

But overall, "Sayonara Kyouhansha" is quite a decent read and can safely exclude itself from stories with shallow plots.