Mnemonic

This kanji has more than one important reading you need to learn, sorry! But don't worry, here's a mnemonic to help you:

When you're writing you need things to fuel you. That's why you always eat buns (ぶん) while you write. Bread bun, hot crossed buns, whatever as long as they're buns, they're great writing fuel.

When buns aren't enough, you call in the monster (もん) that lives under your bed. It pretends to chase you, motivating your writing even further, because if you don't write fast, you'll die by monster bites.