Utakata blows acidic bubbles from his pipe that burn anything it comes into contact with. The sheer multitude and wide-range it can cover makes avoiding it very difficult.
Santōka is the given name of Santōka Taneda (種田山頭火, Taneda Santōka). He was a haiku poet, well-known for his free style haiku lacking the traditional 5-7-5 syllabic rule and seasonal word. He is called a wandering poet for the many trips he took in his later life as a Buddhist monk, wandering through Japan without being part of a monastery.
The san in Santōka's name is actually written with the kanji for mountain (山), but for this technique, it is interpreted as acid (酸), also pronounced san. Tōka is interpreted as meaning permeation (透過) instead of head (頭) and fire (火), which it means in Santōka's name.