Talking about tempra,
I recommend TENYA for you. Because TENYA provides low price and delicious tempra every time.
If you want to classy and reasonable price tempra in central Tokyo, you need a knowledge.
For example, I like Nihonbashi TENMATSU,the tempra-restaurant. Because Tendon(bowl of rice with tempra) of Business Lunch Time(11:00~14:30) is 920 yen and this is a reasonable price.
If you miss the Business Lunch Time, I think that the lowest price dinner of the TENMATSU is 2625 yen, Tokusei-Tendon(special bowl of rice with tempra). 2.8 times price. You will understand that you need a knowledge for a reasonable price food in Japan.

Every restaurant has different service time or don't have it. And many restaurants in business office-buildings area has their own lunch-service-time.

Or if you want to experience a classy service with high price, I recommend the reservation of the restaurant where you want to go.

Talking about ramen,
I'm not worried about a ramen price. You maybe find 390(cheap) ~700(normal) ~1000(expensive) yen ramen. There are many small ramen-shops in Japan. Every shop compete for custom soup of the ramen. Tonkotsu-soup(based on pork bone) is a hot item for travelers from Europe, Shoyu-soup(based of soy-source) is popular and classic in Tokyo, Miso-soup smells sweet, Shio-soup(based on salt) is not so salty, and etc.

Good trip!