Guashiem Blox Fruits: counting your Ectoplasm

Guashiem is a purely informational NPC of the Cursed Ship, in Second Sea: you talk to him, he tells you how much Ectoplasm you have. That's all he does. You can't miss him, he's the only NPC on the ship with a dog or white kitsune head. Since Update 17.3, your total Ectoplasm is displayed directly in your inventory, which makes his service pretty much obsolete.

How to get it

Inside the Cursed Ship (Second Sea). From the entrance (the spawn point), go straight ahead: he stands near the stairs.

His exact role

Unique function: tells you your Ectoplasm amount.
He doesn't sell anything, doesn't trade anything, doesn't give any quests.
Since Update 17.3, the same information is readable in your inventory. The Fandom itself classifies him among NPCs that have become useless.

Spotting him without mistake

From the ship's entrance, go straight to the stairs.
He's the only NPC on the Cursed Ship who looks like a dog or white kitsune: no risk of confusion with the others.

Guashiem, recognizable by his dog or white kitsune look.

Since Update 24, his avatar is sunk into the ground. It's a display bug, not a hiding spot.

Appearance, lore and history

Update 24: his avatar was remade. He now wears a hat and no longer has horns. The old appearance is still visible in the gallery of the source page.

Guashiem's old avatar, with horns, before Update 24.

Lore-wise, the only other NPC to mention him is Experimic: if you try to interact with the latter without Hellfire Torch, he drops an "Ahh... Guashiem...".
A small quirk of the source: the Fandom is uncertain about his gender and calls him both "he" and "she" in the same article. Impossible to determine from there.