That's a small size Natsume (the container for powdered green tea). Here you can see some Eboyas next to a Sailor King of Pen and KoP Pro Gear. From top; small Natsume; KoP PG; mid size Houju; KoP; large size Yatate: Natsume with Pelikan 200, Pilot Custom Heritage 92, Sailor Pro Gear Slim:
I go through the TUL pens like crazy. I go through a lot of ink and do a fair amount of entries. I make all my personal notes and sketches with a Pentel mechanical pencil. 0.05mm. Both are good quality and I don’t have to worry if someone “borrows” them fro my desk.
My work pen is a pilot metropolitan (silver finish) with blue/black ink. Not fancy, but practical and writes nice.
Has anyone else used the Pilot Varsity disposable fountain pens? If you have, you _can_ refill them. You just need a set of needle nosed pliers, preferably bent nose. Grab where the nib is crimped on (behind the shoulder), and pull. The entire 'gilled' section pops out. Then you can clean it like a normal fountain pen, and refill the chamber with ink. I've been refilling mine with inkjet printer ink, left over from old cartridge refills.
I’ve had a few of the pilot varsity pens, and have given a couple as gifts as well. They are good writers, but have never refilled one.
Reasonable, as they're sold as 'disposable'. I just refilled one for the tenth time or so - black inkjet printer ink
I just received an order from pens-n-more (off of ebay, but they have a web site - https://www.pensnmore.com/products/...-pens-medium-point-assorted-colors-pack-of-12 ). Basically, it's a set of universal magnum ink cartridges in a variety of colours (pitched as being for Lamy, but from what I can see, it's better for Parker), and a set of disposable fountain pens. The pens seem to work just fine, and for about a buck apiece, fair value. Not sure why the Orange and Yellow are included, because you really can't see them on paper. Unfortunately, their section construction is more like a Foray pen, or some of the cheaper fountain pens available online, because you can't pull the section out. They've heated and compressed the tube in front of the gill section. I may PIF a couple of the pens just so people here can try them.
Possible highlighter use? FWIW, I have the same pack with all blue ink which I got off Amazon. The pens are .... meh... they write nicely (and a little wet) once they get started. But, the ink flow isn't right on any of them in that they dry up from one word to the next. And it's worse, of course, if they've sat for a while. I suspect that the nib is too tight to the feed, but I haven't played with it. Hopefully, you'll have better luck.
I've used 51s, but something about how the 21 writes appeals more to me. Now If I could ever get my old cobalt blue Esterbrook to write, that would be fun. SMOOTH writing, the brief time it worked for me.