Daikaya or Menya Hosaki are great. You can't do reservations at Daikaya, it's walk-ins only and it can be a bit tight esp if it's just the two of you bc they'll seat you at a bar like table so you sit side by side. For Menya Hosaki, you can't do reservations either but when the restaurant opens you can add your name to the waiting list. That one might be a little more spacious but they have a 90 minute dining limit.

Daikaya is a Sapporo style of ramen meaning its broth is made with chicken, pork, and beef. Oh and Menya Hosaki is only opened Wednesday - Friday in the evenings, but open for lunch on Tuesdays.