Historical clue formulations

• Emperor who abdicated in 2019 after 30 years — 2021-04-15
• Leader referred to as "His Imperial Majesty" — 2014-07-18
• He succeeded to the Chrysanthemum Throne in 1989 — 2011-03-18
• Emperor beginning in 1989 — 2006-05-20
• Japan's emperor beginning 1989 — 2003-04-27
• Establisher of Japan's Heisei era — 1999-10-23
• Japanese emperor beginning 1989 — 1996-03-03