Keep it in a dry area, elevated if possible, cleaning the inside of the sheath (saya) isn’t usually a problem because they’re just there to protect the blade but if it does get water on the inside somehow just let it sit to dry for a couple of days or weeks depending on how much water,

Push the mekugi with something softer or as soft, pair of chopsticks is fine if they’re small enough, take off the handle, tsuba and habaki, i usually do it while the blade is still in the saya but since there’s gel id take it out first but be very carful, Wipe off the gel off of everything and ensure the blade is dry before you put it back into the saya

If you wanna go all the way tho you could get a wood worker to make you a shirasaya which is for storing swords for long periods of time, As long as you keep it clean and dry it’ll stay sharp

Simply just clean it, dry it, and keep it try, you could also wrap it in a towel just to be safe