If you're looking for anime similar to RIF: Aimai na Mama, you might like these titles.
Set in a mechanical world, Mechronicle tells the story of Mechanico: a small, shy, withdrawn boy with big glasses. He is totally in love with Nell, who looks after Mechanico like he's her kid brother. One day, Nell is kidnapped by Team Magu Magu, a villainous group of machines. She soon discovers that the secret to their world is hidden in her machinery. Mechanico vows to rescue Nell and, plucking up his courage, pursues the kidnappers. The adventure begins!
In the distant future, mankind attains longevity through gene manipulation. However, in exchange, the ability to reproduce is lost. Clones were built to maintain the dwindling workforce, but 1,200 years ago they rebelled. The humans, suddenly finding a need to understand their subterranean-dwelling creations, launch an ecological study.