Chako is a robotic cat that was abandoned by her old owner and left for scrap. She was about to be thrown into molten lava when Luna's dad rescued her and rebuilt her to give to Luna as a present. At first, Luna hated Chako. She later found out that she and Chako had a lot in common, and gradually warmed up to her. Chako originally got onto the field trip space ship by sneaking her way aboard. She helps Shingo out with most of the electronic and technical problems.

(Source: Wikipedia)