Hotaru (ほたる; meaning Firefly) Ramen, with additional egg.
Since the soup was not bright red (the black liquid is garlic oil), I did not think it would be that spicy. This ramen was actually very intense, about the same as the Spicy Miso ramen from Nakamoto I posted about some time ago. This was with the default level of heat (level 1). It can go up to level 20 but the max level will probably blow a hole in your guts. The heat comes from habanero chili pepper: There are red bits of the stuff floating in the bowl and mixed with the noodles.
I found out about this shop from the 2014 issue of Ramen Walker (Tokyo edition) that I bought a couple of weeks ago. The magazine lists many noodle shops in Tokyo, with opening times and some info about the menu.
This issue has a special feature about some guy doing a Spicy Ramen challenge that involves going to restaurants known for the heat of their ramen and ordering the spiciest thing on the menu (I think: My Japanese is not very good). I have been to about half of the shops listed (although I did not go for the spiciest item: I still want to enjoy what I eat) and I plan on trying the rest in the near future. The spiciest ramen in the list is the so-called Oroqen Megafire from Do Miso in Ginza (I posted about the normal spicy version here).