Androids

There are other permanent hearts too, but Beryl one is the most readily available because everyone can get one from Hot Time. The others, while still completely tradeable after equipping, may be a bit better, but they come from NX-only CS Gacha Box events. Best one being the Superior Lidium Heart (it's just a name, not a Superior item, as in, the property), which is not only permanent, but it has two more slots and is, unlike the other perma hearts, which are level 30, level 80, so it receives 3rd Tier potentials.

Oh boy, more NX milking, tough luck for these damn hearts then.