Apparently, Matsugen is offering Sea Urchin Bukkake.
"Yes, it is a kind of cold udon." (Via Balk.)
Related: "Bukkake is the noun form of the Japanese verb bukkakeru (打っかける), meaning 'to splash forcefully.' The compound verb can be decomposed into two verbs: butsu (ぶつ) and kakeru (掛ける). Butsu literally means to hit, but in this usage it appears to be an intensive prefix as in buttamageru (ぶったまげる, 'completely astonished') or bucchigiri (ぶっちぎり, 'overwhelming win'). Kakeru in this context means to shower or pour. The word bukkake is often used in Japanese to describe pouring out water (or other liquids) with sufficient momentum to cause splashing or spilling. Indeed, bukkake is used in Japan to describe a type of dish where the toppings are poured on top of noodles, as in bukkake-udon and bukkake-soba."
