Began with a photo on Temu: https://www.knittingparadise.com/threads/how-to-knit-this...

This swatch is following instructions at:
https://nimble-needles.com/stitches/how-to-knit-the-doubl...
With thanks to Knitting Paradise’s member Curmudgeon!

Initial use of cubical interchangeable needles - with swivel - from Temu.

What a strange quantity of yarn for a skein!! 84 grams! That’s 2.963 ounces. Did there used to be 3-ounce skeins of worsted weight yarn? I remember 4-ounce balls, but I think lower number of ounces was usually reserved for thinner yarns. However, this is the first time I see yarn made in Japan. Maybe their standard put-up … I don’t know.

Crochet-hook cast-on 24 stitches - 8 on each end for the selvedges, and 8 for the centre stockinette.
Twenty rows stockinette and twenty rows garter stitch.