There was an earthquake with a magnitude 6.2, but it was harmless.
What's with people who troll even harmless tweets?
Don’t worry. Tofugu doesn’t have any poison. He’s a harmless blowfish.
Psh, that guy's damage is nothing. He's what I'd call "mostly harmless."
This is a jukugo word, which usually means on'yomi readings from the kanji. If you know the readings of your kanji you'll know how to read this as well.