Santouka is actually a restaurant chain. I have not tried the one in San Jose yet, but I did for NJ and Chicago. Both of them are also inside Mitsuwa.
Their ramen is actually very good on the Tonkotsu type and close to what you get in Japan. If you want to try other place, you can try:
Ramen Halu - really close to Mitsuwa
Ramen Santa - San Mateo
Maruichi - Milpitas
Honestly, I am not a big fan of Kahoo.
Well, I guess different people has different taste profile, that is why so many different ramen in Japan. The latest trend in Japan is a blended soup.