The title story is about a relationship between a high school teacher (Ando-sensei) and his student (Ikoma), but that's not where the real guilty part kicks in. It appears that Ando is/was a shota-con and tried to do the deed with Ikoma when he was a lot younger (yes, Ando is rather aged; perhaps about 40-ish). Ikoma got away, and now is making a move on Ando in high school. Ando, though, is full of angst, second thoughts, and, like the title suggests, his own guilt.

"Risky" is the second story, and is about 2 brothers that live together. At least, I think they're brothers. One refers to the other as "brother", but there are instances where one is referred to as "-san." Maybe they're kids of family friends? Either way, this relationship is questionable.

Kaga Yoshitaka is the younger one that cleans and looks after his elder, Hashizume, who comes back late from work drunk. Yoshitaka acts like a harried housewife that takes after her salaryman husband. It's not too far from reality, except Yoshitaka is a student.

"Kimi sae ireba" is the short story prequel to ... Kimi sae ireba (ahaha). This is where I start getting some basic info from mangabonbons.net. Machida Kouzou (Machida-san) is the father-in-law of Machida Kenjirou (Machida-kun). They're both widowers, work in the same place, and boy howdy does Machida-kun want Machida-san. He pursues his father-in-law, who is understandably more than a bit wary about this relationship. Hey, it's the Oedipus/Electra complex. Only, for yaoi!

The last story, I don't know the name for, but it means something like "Teacher B." Obviously, another story about student-teacher relationships. Asada is a cheerful student with no concept of personal space, and is constantly jumping all over Kono-sensei in a platonic kind of way. Platonic, because Asada is getting done by Shina-sensei, who is rather reserved-looking. Strangely, Asada and Shina haven't gotten caught yet, despite their propensity for doing it on school grounds. Which is how Kono discovered them.