This is a strange little tale but one I quite enjoyed and would recommend to people looking for something a bit different from the usual BL fare. Its style reminds me of mangaka like Takaido Akemi and Takaguchi Satosumi with a similar cast of slightly odd characters. Here follows a somewhat detailed summary of the story (no spoilers) which you'll need if you're reading the GG translation...
Tora is a naive geeky type who's usually caught up in his research. His one friend is Amane, a beautiful alluring guy. Amane invited Tora on a trip but got angry when the oblivious Tora didn't realise that it was meant to be just the two of them. On the scheduled day, unknown to the other the two make their ways separately to the pre-planned destination and bump into each other. Amane has brought three friends along with him and Tora ends up joining the group. At the beginning of the trip, Amane tells Tora that one his friends has just broken up with his girlfriend and is depressed so the group are forbidden from mentioning anything to do with love. Amane refuses to tell Tora who it is because Tora's the type to reveal everything on his face. Amane then adds that his ex-boyfriend is also on the trip, and again, doesn't say who it is. So the story turns into a sort of mini-mystery, with Tora playing bungling detective trying to figure out who's who.
Although the group don't get up to anything exciting (Tora, a dam otaku, takes them on a tour of dams...) there's a definite atmosphere of intrigue throughout. We're shown snippets of flashbacks of Amane's relationship with his ex and it becomes clear that the ex is a troubled individual. A couple of the friends behave suspiciously on the trip and are alternately hostile and friendly towards Tora, leaving Tora very confused.
While this is going on, Tora and Amane are making up after their argument and growing closer together on the trip. However, Amane, who wants to act like his usual cool unruffled self in front of his friends, restrains from showing too much of his feelings for Tora. The couple are awkward, sweet and quite cute when they open up to each other. I like the character of Tora who's completely clueless when it comes to love and has to rely on Amane to guide him.
There's a pretty even balance between mystery and romance, and the mystery side of the story automatically sets apart this manga from your average BL. The kooky characters, the intrigue, the slight tone of menace that arises from not knowing if the mystery ex is going to do something to Tora, this all combines to create an interesting little story that's engaging to the very end. The epilogue chapter is about Tora and Amane after they finally get together and is hilarious, it's seriously worth reading the manga just for the epilogue.
A note on the GG translation: it's confusing... At first the translation tells you that the broken-hearted guy is also the ex-boyfriend so you read the story thinking there's just one mystery guy, but as the story progresses you work out that there are actually two mystery guys. It's the job of a mystery to mislead the reader but it's obviously not helpful when the translation adds its own layer of confusion.