Viet has decided to leave the Yakuza group and follow the teachings of Buddha.
Koichi is always as cool as Buddha and as strict as Yama, the King of Hell.
There are some proverbs related to Buddha like, "what you don’t know can’t hurt you," and, "the crushed worm will turn."
The kanji and the word are exactly the same. That means they share meanings as well.
Since this word is made up of a single kanji, it should use the kun'yomi reading. When learning the kanji, you didn't learn that reading, so here's a mnemonic to help you with this word: You go up to Buddha. You want to rub his head for good luck, because that's what you hear is good to do. Right before you touch him, he backs off and says, "Whoa! I'm hot, okay?" (ほとけ). You touch him and it burns your hand clean off.
Imagine saying "hot, okay?" in a strange accent to help you to remember.