Keyaki
This ordinary-looking 10-stools-at-the-plastic-counter joint in Susukino has had lines of faithful slurpers outside since the year 2000 (a lifetime for a ramen shop) and is still chopping, boiling, and serving its succinct seven-item ramen menu. Order from the vending machine at the door then wait on the bench or stand around the corner; once seated wait for the cook to hand down a steaming bowl topped generously with vegetables from the raised and hidden kitchen.
If you want to keep your clothes clean, don't avoid slurping, just accept the paper bib they offer.