Su-san's (蘇さん) full name is Strength. She is Rock-chan's friend and possesses a tendency to do things her way, often an attempt to test Rock-chan's patience. She often uses her robotic arms to toss objects (even Rock-chan herself) into the air and is even more destructive when throwing a tantrum. Her personality causes Rock-chan to take up an older sister role.
Her appearance is very similar to Strength in the OVA and Anime. She has white hair, a black hood, dress, gloves, and boots as well as a short tail. Su-san doesn't always have Strength's robotic arms but there are a few times that she does.
Su-san has a very quiet attitude but loves playing. She doesn't talk very much.