Maybe a little education on Japanese registration and tax laws: Everything above 400 cc is ridiculously expensive in Tenno's country. And forget about foreign imports, they are taxed even worse!
That's why they have all these pretty shrunk sports bikes like the CBR400RR (Baby Blade) and before that th 350 and 400 Fours.
Apart from that: What else do you want on a weak bike, but really good suspension and huge brakes? I've seen good riders on a 125 taking out Mr. Fancypants Superbike all day long on the race track!
Brake later, and corner hard! That works with a ninble 400 better than with anything else.