Datirimon

Datirimon is a Slime Digimon whose Japanese name is derived from the onomatopoeia for whistling (『ぴいぴい』), whereas its English name originated from a competition run by YTV where whoever won would get the chance to name this Digimon. It is said to appear to humans who have regained once-lost wishes.

Digimon Adventure 02
Datirimon was once Yukio Oikawa's partner, but they separated because Oikawa was about to die when they first met. After MaloMyotismon is defeated, Cody Hida helps the dying Oikawa to the entrance to the Digital World, where Datirimon reappears. With Datirimon's prodding, Oikawa recognizes him as his partner. Oikawa then decides to follow BlackWarGreymon's example and convert his essence into spiritual energy to prevent any evil from returning to the Digital World, though his sacrifice saddens Datirimon.

Digimon Frontier
A Datirimon is seen at the Autumn Leaf Fair.

Digimon Data Squad
A Datirimon is seen in a glass stasis tube in the lab where Kurata's men were going to operate on Thomas' sister.