I'd noticed Yasuo mentioned in magazines, on blogs, and even on a narrow search of highly ranked shops in my neighborhood. I've known about them for years.
Why did it take so long? Well, they are in the realm of jiro-kei; shops that serve ramen in the style of Ramen Jiro.
Jiro is not my cup of tea. Mainly because I don't like my tea to make me stink of garlic and rendered pork fat for the next 12 to 18 hours.
I shouldn't judge, though. While the ヤスじろう option is strictly jiro-kei, the others aren't quite at that level. Go for ラうどん - ra-udon - if you like your noodles super thick, or ラそば - ra-soba - if you like them thin.
Most people go with the thick ones, and most people come back.
If this is jiro-kei, then it is officially my favorite bowl of that genre. The noodles are the bomb, and the soup intense but drinkable. Spinach greens play nicely with a very meaty bowl, giving it some healthy vitamins. Most Jiro style bowls are covered with nutrient-lacking bean sprouts and cabbage.
And as I had nothing to do the rest of the day, I added a bit of freshly minced garlic. Definitely recommended.
Tokyo, Shibuya-ku, Yoyogi 2-29-3
Closest station: Minami-Shinjuku