KanjiJLPT N5
Book

book, present, main, origin, true, real, counter for long cylindrical things

Mnemonic

One slash marks the base of a tree. An old librarian carved it there to remember where she buried the world's first book. The book's pages grew from the tree's own roots — living knowledge, rooted deep, waiting for someone to dig it up and read.
Additional thoughts
The horizontal stroke (one) cuts across the lower trunk of the tree, visually marking the root. Books are the root of knowledge, just as this mark indicates the tree's foundation. Picture bark-pages sprouting from the earth beneath that carved line.
Quick recall
One slash at a tree's root marks where the first book lies buried.

Details

The keyword for 本 is book. This kanji originally depicted a tree with a mark at its base, indicating the root or origin of something. From this sense of "origin" or "foundation," it came to represent books as the fundamental source of knowledge and learning. It is one of the most commonly used kanji in Japanese, carrying meanings related to books, origins, and the concept of something being primary or true.
On'yomi
ほん
Kun'yomi
もと

Used in kanji