KanjiJLPT N1
Luxuriant

luxuriant, thick, overgrown, frequency, complexity, trouble

Mnemonic

Grandma's garden is unbelievably luxuriant — every inch overflows with thick, lush growth. Her secret is pure cleverness: she learned ancient composting tricks that make soil explode with life. Neighbors beg grandma to share her methods, but she just winks and keeps her garden thriving.
Additional thoughts
Picture grandma surrounded by impossibly dense, towering greenery — vines crawling over fences, flowers bursting from every crack. Her cleverness is what fuels this overwhelming abundance. Cleverness on top, grandma below, together producing wild, unstoppable growth.
Quick recall
Grandma's cleverness makes her garden impossibly luxuriant.

Details

The keyword for 繁 is luxuriant. This kanji conveys the idea of things growing thickly, abundantly, and flourishing in great profusion. It is used to describe vegetation that is lush and dense, as well as more abstract concepts of prosperity, complexity, and proliferation. By extension, it can also refer to things that are frequent, busy, or thriving with activity.
On'yomi
はん
Kun'yomi
しげ.る、しげ.く