Fugu is a bit on the wild side, but very kind despite his appearance.
This is a single kanji with an い on the end, meaning you know it's probably an adjective. What's the adjective form of gentle? It's gentle (but also kind or warm hearted).
Since this word consists of a kanji with hiragana attached, you can bet that it will use the kun'yomi reading. You didn't learn that reading with this kanji, so here's a mnemonic to help you: What do people who are gentle and kind say when someone asks of them a favor? Always "yessir" (やさ). Always, always "yessir"!