It's the boys' love manga with baby-faced talking penises. Oh, and body-swapping. The series begins with magical penis-swapping, so the boys enter each other's penises. "From the impact of the accident on our school field trip, Ayase's penis is now possessed by my spirit."
It's weird, but amusing. I enjoyed it, albeit in a "what the hell" way. However it's basically porn, written by and for women who like boys' love. It's not explicit hardcore, but sometimes it's not a million miles away. If someone's performing fellatio on his teacher after school and you can see the penis in his mouth with only the glans censored, for instance, does that count? The manga also becomes absolutely bloody terrifying when Toride-kun's little brother becomes part of the story. (Caveat: I haven't read the whole manga, so I don't know exactly how bad this gets. Please don't tell me.)
The story itself is fine. It's all about everyone's emotions, relationships and penises, obviously, so you can think of it as a very surreal soap opera. Sometimes the heroes are being written as women in men's bodies, but that's normal for this genre. However the hot gay sex is side-by-side with adorable penis character comedy. The penises are cute. They'll argue with you, lecture you and have opinions on your love life. They can find dropped objects by smell, if you give them a chance to sniff the ground. (There's a mental image to carry around with you.) They wear clothes if it's cold. An annoyed penis in little coat, hat and scarf is one of the funniest things you'll see all day.
"The days of cold are overflowing with love for penises."
Almost any line of dialogue on any page is capable of being the most insane thing you've ever read. "A few months have passed since the accident during the graduation trip. Ever since then, I have been living happily as Ayase's penis."
There's a scene where everyone has their flies unzipped and their penises hanging out, for an eight-way four-man conversation. Ayase and Toride-kun are like a phallic X-rated equivalent of Midori Days. There are even parallel scenes, e.g. the chapter where you visit your unconscious partner's real body in hospital and get caught by their mother doing something unfortunate. Guess which manga goes further. Seiji might have helped Midori grope her own boobs, but he never put his penis in the rectum of a coma victim. Good news: Toride has an understanding mother.
The best bit isn't any of that, though. That would be CHINTSUBU THE INSIDE STORY, aka. NASE-CHAN'S PENIS DIARY. This is a diary segment in which Yamato Nase tells us about herself, her life and her manga creation process. It's brilliant! I found it far more entertaining than the main manga. She doesn't do a diary after every chapter, unfortunately, but I always thoroughly enjoyed reading them. I laughed at things like Nase and her editors going to a pig testicle restaurant and then afterwards going on a post-testicles drinking bender, chanting "penis penis". They visit the Unusual Treasures Museum. (Afterwards: "I feel like I'm going back to being a normal girl from being a weirdo.")
"Will it really be okay to draw such a strange manga? Having talking peepees... Ah well. Drawing them is fun, so I'll just do it. Talking peepees are fuuuuun. Whatever happens, it'll be fine, because it's a manga. Having talking peepees is okay, because it's a manga. It's a weird manga, but it's okay, because it's a manga."
It then becomes a CD drama. Nase's brain explodes. Yes, this talking penis manga sold well enough to get a spin-off CD drama.
That was funny, but there's also utter "I can't keep reading" terror.
Volume 2 Chapter 9 is pretty scary, but nothing happens. Toride bathing with his little brother shouldn't be a difficult scene to read, but you'll be living in fear because you wouldn't put anything past this manga.
Volume 2 Chapter 13, on the other hand, is screaming brain bleach time. The manga gets horrifically, appallingly close to some terrifying lines. You will never see this volume in an English-language bookstore. If you do, expect to see a mob with burning torches.
It's weird and often funny. It's non-stop filth. I'm pretty sure it's unique. You can read the first two volumes without needing to be arrested, but don't blame me if you continue beyond that. (It might be fine, though. I don't know.) It's worth reading just for NASE-CHAN'S PENIS DIARY, though.