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Siro Bikini


Slip into something a little more comfortable with just enough coverage. The Siro Bikini underwear are an essential every night sleep underwear that are so comfortable you’ll forget they are even on. Constructed with a fine, shrink-resistant Japanese elastic waistband, breathable Siro Modal cotton, and flattering bikini cut silhouette. Pair with the matching Siro Bralette or mix and match colors. For a more full coverage option try the Siro Sleep Brief.

  • Medium coverage
  • Sits at hip
  • Soft Japanese elastic waistband
  • 95% siro modal and 5% spandex
  • for sanitary reasons, all underwear orders are final sale
  • Made in Los Angeles


Runs true to size but if you are typically between sizes, we suggest you size up.

Model is wearing an S. Height: 5’9, Waist: 25", Bust: 34" Hips: 35"

Unsure of your size? No need to lose sleep over it - we are here to help! To ensure proper fit, please refer to the fit guide below and if you have any questions, visit Lunya's Fit Guide - we are happy to guide you!

Size XS S M L XL
Numerical 0 2-4 6-8 10-12 14
Bust 33 34-35 36-37 38-39 40-41
Waist 26 28 30 32 34
Hip 36 37-38 39-40 41-42 43-44
Inseam 30 30.5 31 31.5 32

Measurements are in inches and refer to body size, not garment dimensions. Please note that fits may vary by style and personal preference.

Need help with your size? Have a suggestion or feedback?

Lunya gladly accepts exchanges and free returns of unworn/unwashed items with the original tags attached within 30 days of your order ship date. Underwear, Gift Cards, & Sale Items are nonrefundable. Please email to initiate a hassle free exchange/return or with any further questions. THX!

The Difference

Thoughtful Fabric: Siro Micro Modal is an environmentally friendly, sustainably produced fabric known for being extremely smooth, soft, and cool to the touch. The fabric is resistant to shrinkage, fading, and hard water deposits (so it stays soft). It’s also extremely breathable, excellent at absorbing moisture, and shows minimal pilling. The 5% spandex allows freedom of movement without bunching.

Intelligent Design: We carefully designed this bikini style with a double layer to minimize translucence, offset seams to keep everything smooth near your lady parts, and topped it off with the finest Japanese elastics.