also: りゅっくざっく · るっくさっく · るっくざっく
A backpack is convenient for traveling.
彼はリュックサックに教科書を詰めた。
He stuffed his textbooks into his backpack.
He walked along the mountain trail carrying a large backpack on his back.
I put water and food into my backpack.
Since I was tired, I took off my backpack and rested.