Most popular foreign cuisine in Japan is Chinese cuisine. Chinese food can be eaten anywhere in cities throughout Japan, but the taste and the menu are adapted to Japanese style.
In europe, all Chinese restaurants are run by Chinese or people from neighboring countries of China but many Chinese restaurants in Japan are run by ordinary Japanese who never lived in China. This applies to Italian and French restaurants in Japan too. Chefs of theses restaurants might lived in Italy or France but never grew up there.
On the other hand, all Indian restaurants are run by Indian or people from neighboring countries of India as like in Europe. It is interesting that probably there is no Indian restaurant which is run by local people only.
Indian restaurants in Japan offer lunch menu which includes main dish, naan or rice, salad and beverage less than JPY 1000. If you want to eat something spicy, why not try Indian dishes in Japan?