Being a huge fan of GTO. I decided to explore other manga related to it and finally came across this. I really liked Ryuuji, not as much as Onizuka but he was a fun person as well. This spin off revolves around Ryuuji and his short (mis)adventure after meeting a girl named Mimon.

I would say that it's a classic GTO story but with Ryuuji as the protagonist. The characters from Shonen Junai Gumi/GTO do show up but they don't have a major role here. There are crazy bike chases, cars crashing around, robbery equipped some ecchi and sexiness with some bra and panty shots. The new female character was good and Ryuuji's relationship with her was fun to see.

The art is pretty much the same as GTO. For it's short length of one volume I really did enjoy it.

If you are a fan of GTO and Shonen Junai Gumi, GT-R is definitely worth the read.