Recommended bowl: Kappo Mazesoba

Ichiryuan is best known as a Japanese kappo and sushi restaurant. But owner Takino-san is a major ramen head, so aside from offering a killer omakase and various high-quality sakes, the place also serves a limited number of bowls of mazesoba (available for lunch on Wednesday and Thursday, or via advanced reservation). You choose between two options: mazesoba with truffle, or topped with a small spoonful of spicy chili paste. The noodles are handmade by the nearby Ikebukuro ramen shop Rock'ando. Toppings include pork and chicken chashu, raw egg, green negi, chopped onions and sprouts. This is a legit, totally off-the-radar back street restaurant.