‘Zuisen no Shiro’ is a matcha favored by Grand Master Hoensai of the Urasenke tradition, at the Kyouan teahouse.

"Urasenke" is one of the primary schools of the Japanese tea ceremony.

"Kyouan" is the name of a teahouse.

"Hoensai" is the title of the Grand Master (or highest-ranking master) of the Urasenke school.