A special two-part episode that aired between episodes 24 and 25 of Dr. Slump: Arale-chan.

On Filiel's 15th birthday, she received her mother's necklace as a memento from her obstinate astronomer father. Her common and tedious life was turned into a life of conspiracies. With her new life, many adventures await. (Source: ANN)

Daisuke Niwa is a clumsy, block-headed, and wimpy middle school student who has few redeeming qualities. On his 14th birthday, he finally decides to confess his love to his longtime crush Risa Harada, but is rejected. In an unexpected turn of events, however, Daisuke finds himself transforming into Dark Mousy, the infamous phantom thief, whenever his mind is set on Risa. Though Daisuke is unaware of this strange heritage, his mother is certainly not: since before the boy was born, his mother had been planning for him to steal valuable works of art and let the name of the elusive art thief be known. With doubt and confusion constantly clouding his mind, Daisuke finds himself struggling in his relationships with classmates and family. And it is not long before Daisuke realizes that he is not the only one with a fated family legacy—his greatest adversary could be the one classmate he is most unwilling to fight. [Written by MAL Rewrite]

The 11-year-old Marui triplets could not be any more different. The oldest one, Mitsuba, is sadistic and kind of mature for her age. The middle one, Futaba, is perverted and very athletic and has the strength of a full-grown man. The youngest one, Hitoha, is generally very quiet and gentle but when push comes to shove, she might just be the strongest, the most perverted and the most sadistic out of the three. The three are all in the same class, led by the newly graduated teacher Yabe Satoshi. He usually gets pushed around by the girls and, on occasion, abused but the triplets also try to lead him and the new school nurse, the clumsy Kuriyama Aiko, together. However, Yabe had no intention of dating Aiko and the methods the triplets use to accomplish their goal are highly unorthodox...