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: You're waiting inside. The remainder of your forces are out there, fighting. You don't know who will survive... or if they even will. You have a secret knock (のこ), though, that you use to find out if it's one of the remaining forces outside or the enemy, broken through. You hear a knock. What is it? Is it your men or theirs? Imagine it out, focusing on the knock conversation that happens between you and the remainder.
Where is the leftover water?
Koichi's tweet last night made even the small remainder of his followers very upset.
I’m going on a date tonight. You can heat up some leftovers from lunch to eat for dinner. Love, Mom.