2x18 - Mew Mew Power

Ryou and Keiichiro learn that mew aqua may have been made by the aliens when they inhabited Earth. A strange type of energy begins emerging in Tokyo and trees grow out of control, turning the city into a forest. The Mew Mews find something that appears to be a large mew aqua in a tree but before they collect it, Tart arrives and turns the tree into a chimera anima. During the fight, Mew Ichigo realizes that Ryou cannot be the Blue Knight as they both appear at the battle to aid her. The Mew Mews defeat the monster, but they are unable to figure out what caused the forest to appear in the first place.