The most interesting part is that the reader can follow a Yakult bottle as it travels through the ocean. Even though it is a picture book, the illustrations are very impressive. The part that left the deepest impression on us is at the end, when the Yakult bottle avoids being eaten by a big fish but gets tangled in sea plants. The plants die, and only then can the bottle escape and float freely.

The author uses simple drawings to show a serious fact: if a sea creature gets tangled in a plastic bag, it can only be free when it dies. After death, the body has no weight, and the plastic can float away to meet another living creature.