you can get a perilla star from completing a season, it is one of the rewards. you can recharge it as well, and upgrade it too (although that is not a popular choice). check out jetina and fughar after you do a season to see all of the choices you have with gear, accessories, and other upgrades!

As lady mentioned, it is a seasonal reward. The quest to get it is very easy, and honestly, the story is pretty good. You will need to complete the quest via Fughar before you graduate seasonal. The link that follows is what will tell you which quest begins the quest line! [Perilla's Star] For You - BDO Codex

Now, before the Ators stone coming along, Perillas was a good alternative for grinding PVE in lower places because of the defensive stats it gives. I will also say, some people do use fully upgraded Perillas to grind at certain high end spots, but their ap is way up there.

As a side note, DO NOT get Perillas Star as a seasonal reward first. You will want to prioritze the PEN Capotia Ring, PEN Capotia Necklace, and PEN Capotia Belt first. Get the one that gives the most ap to you first, then get the next big increase, then the last one. Then get the Perillas Star. Perillas star is nice to have for an alt for example.