I don't have any masturbation material on my hands, so to speak. Instead of keeping it hidden which takes up space, real or virtual, and brings the risk of being caught, I decided, about 8 or 7 months ago, to create an account on a porn website and every video or picture I found, I upload there and mark it private so that only I can see it which eliminates the risk of getting it removed by copyright.
I couldn't be happier about it. I keep everything I like, there's no risk of losing it, no risk of getting caught so long as you clean your search history and you have everything you like in one place. The only downside is that downloading + uploading and (if you're OCD like me) organizing takes a long time.
I don't really hide it. My physical copies are stored in a large long box beside my futon for easy access along with my onaholes. my digital copies are stored in my desktop pc I don't use external hdds because I still have space in my computer which is around 1.3tb
I don't have any physical form of hentai so I just use my computer. I don't keep any Doujins and such on my computer though, only a handful of NSFW pictures only showing exposed tops and such on my desktop in a folder.
Never needed to hide hentai. I don't really have any on my computer. I do have some visual novel cgs but that about it I just read here on fakku and no one else uses my laptop really.
No one ever goes on my computer when I'm not around, so I have no reason to hide it. Even if they did, I wouldn't care if they found my stash and were appalled; their fault for snooping.
Regardless, I keep it on my 2nd internal HDD.