This is an educational manga that sparked my second-grade son's love of reading. The series teaches about ecosystems by comparing the combat power of creatures in the natural world based on scientific data and determining their wins and losses. The series has surpassed a cumulative circulation of 4.4 million copies in Japan. This is a set of four books that particularly interested my child. They are in relatively good condition and I think they are clean. "Lion vs. Tiger: Battle of the Land's Strongest Kings" "Mantis vs. Scorpion: Who is the Strongest Assassin!?" "Snakehead vs. Piranha: The Terrifying Biting Squad" "Orca vs. Hammerhead Shark: Terror! Sea Killer Showdown"