User blog comment:Crimson and Darkness/Volume 25 discussion blog/@comment-2405:205:118C:74F6:6897:6E90:B47B:C2B5-20180424035204/@comment-31654305-20180424042252

isse use amrita, amrita is miracle cure that he receive during his training wit indra

source http://boards.4chan.org/a/thread/171803246#p171880090 (Issei's talk with Chichigami in v25:)