Mystery (ミステリーちゃん, Misuterī-chan) is a Ham-Ham who appears in some of the Japanese episodes.
Mystery is a fortune-telling hamster. She is able to predict the future with her magical crystal ball. The catch is that she only predicts obvious things that the Ham-Hams already know, or she makes very vague predictions that could apply to anyone. The Ham-Hams are often suspicious of the veracity of her fortunes, but still often go along with them anyway.
Mystery is never seen without her pink costume; she even wears it while sleeping. While channeling her predictions, she chants "atarinchu~" and occasionally ends her sentences with "pitarinchu~!"
Mystery is very cheerful and optimistic, and she never becomes angry with anyone or anything. She is very confident with her predictions and is always certain they'll come true.
In Lady Lapis!, Magical mentions waking her up would be bad, which could mean she can be cranky if woken too early.
Magical is Mystery's little brother and assistant. He too is very confident in his sister's predictions and will become angry when anyone questions them. He mostly does a lot of the talking for her. She may not be very talkative in general, or perhaps she is too concentrated in her fortunes to respond to most inquiries.
See also: Mystery/Gallery