This is what I came up with for converting to English & knit-in-the-round…
Japanese pattern by Yukiya found here.
I'm sure there are errors, but I don't have the time or the desire to work it out...at least it's a place to start.
This pattern will give you a FO sized for a small adult woman...since it is for "panties" not "baby pants."
Approximately DK or sport weight
Size 6 or 7 needles
19sts & 26 row in 10 x 10cm
Knit in the round starting at center back.
Cast on 144sts.
Round 1: Work K1, P1 ribbing. Place marker at center front & center back
Round 2-4: Work K1, P1 ribbing.
Round 5: Work eyelet row
Round 6-9: Work K1, P1 ribbing
Round 10: Work K1, P1 ribbing increasing by 32sts evenly around
Round 11: Knit 38sts. Place marker (back right). Work side ribbing (K1, p1, k2, p1, k2, p1, k2, p1, k1). Knit 76sts. Work side ribbing as before. Place marker (back left). Knit 38sts.
Round 12-69: Repeat Row 11.
Round 70: Knit 8sts placing them on a stitch holder. Continue as previous round until 8sts before center front marker. Knit 16sts placing them on a 2nd stitch holder. Continue as previous round until 8sts before center back. K1, then place it and the other 7sts onto the first stitch holder w/o knitting them.
On straight needles for 15 rows, K1, P2, K2, P2 repeat * until last stitch, K1.
Row 16: Knit entire row. Work kitchener stitch to join to 16sts on 2nd holder.
Divide 144 sts for legs evenly onto circular needles or DPN’s (72sts ea).
Round 1: Knit around grafting 16sts along gusset piece.
Round 2-15: Knit around
Round 16: Knit around reducing by 10sts evenly.
Round 17-22: Work K1, P1 ribbing.
Round 23: Knit around increasing by 20sts evenly.
Round 24-28: Knit around. Cast Off