Class (分類) is the class of the monsters.
(ミズグモ, "Water Spider")
Species (種族) is the type of mutation from monsters. The mutation system from the series allow monsters to become stronger and adapt to different environments. To cause a mutation, the monster must be under environmental stress. The stress is caused by massive loss of lives. There are three different stresses that trigger ether basic, abnormal, or giant breeds. Other mutations occur under special conditions.
- Basic (基本) - Basic monsters with balanced strength and fertility. Occurs when threatened by heroes.
- Abnormal (異常) - Power and vitality are lower than Basic types, but they have high fertility and special abilities such as poisonous and paralyzing attacks. This breed happens when predators are on the prowl, requiring the species to be sly to survive.
- Giant (巨大) - Has high vitality and power, but low fertility. Will canibalize other giants to become stronger. This breed occurs when there is a scarcity of food, with the monsters starving.
- Pure (プレ) - Monsters that can't mutate. Due to this they usually having low stats. During a mutation, there is a small chance this will be the result. It only affects one monster. In the third game this also happens when monsters are pufied with holy water.
- Rare (レア) - Mutation achieved under special conditions. The conditions depend on the monster:
- Mosses - Have near the same amount or more Lizardmen than Mosses.
- Spirits - Have a massive amount of spirits.
- Insects - Mutate into a Pure Omnom three times in a row.
- Lizardmen and Liliths - Mass death caused by eating trap food.
- Almanac (What Did I Do To Deserve This, My Lord!?)
- Almanac (What Did I Do To Deserve This, My Lord!? 2)
- Almanac (No Heroes Allowed!)
- Monsterpedia (No Heroes Allowed: No Puzzles Either!)
- Monsterpedia (Yūsha no Kuse ni Ko Namaiki da DASH!)