He was initially a priest of the Nichiren sect; however, he converted to the Tendai sect and entered Mt. Hiei and learnt from Echo, Gocho, etc. At the time, Buddhism was criticized by Confucian scholars and scholars of Japanese classical literature, and Entsu thought that the decline of Buddhism was caused by the development of astro-geography, and thus he mastered the study of the calendar of India. As a result, in 1810 he wrote 5 volumes of "Bukkoku Rekishohen" (literally, "study of the calendar in India") based on the astronomy of Mt. Sumeru (in Buddhism - said to be the highest mountain rising in the center of the world). Tadataka INO offered a counterargument to him in "Bukkoku Rekishohen Sekimo" (literally, "to eliminate the wrong idea of Bukkoku Rekishohen") and Shingen TAKEDA in Osaka engaged in a battle of words with Entsu, who was visiting Osaka, and argued Entsu down. Entsu first resided at Chishakuin in Yamashiro Province, and later, he resided at Zojo-ji Keisho-in Temple in Edo.