Ryakko shugyo is the ascetic practices which a bodhisattva (one who vows to save all beings before becoming a Buddha) does for a long period of time while being reincarnated over and over for three generations, past, present, and future.
歴劫修行（りゃっこうしゅぎょう）とは、菩薩が長い間、過去現在未来の三世において転生を繰り返して修行すること。