Onipan!

Over the centuries, oni (AKA demons of Japanese folklore) got a pretty bad reputation. Now it’s up to three plucky oni kids — sunny Tsutsuji, cool Tsuyukusa and boisterous Himawari — to improve human-oni relations through love, friendship and superpowered underpants!
(Source: Sentai Filmworks)
Note: Aired in 2 versions, a 60-episode 3-minute short series, and a combined 12-episode 14-minute TV series with the same content. Each episode of the combined version is 5 parts of the original.