Traditional Japanese food (washoku, 和食) could be described as "subtle", "delicate", or maybe "mild" -- in other words, bland. The strongest flavor you're likely to encounter is pickled vegetables.

Luckily, Japan has a long history of importing recipes from other cultures, for example ramen. I live in Tokyo and haven't had much success locating spicy Indian-style curry, but Sichuan-style dishes are widely available and will blow your tongue off if you're not expecting it (I didn't know what 四川 translated to at first, but I made sure to look it up later...).

Having enjoyed Japanese food all around the world, including when I lived in Japan, speaking personally, "bland" would not be my first adjective, but ¯\_(ツ)_/¯