In a new “Comment Defenders” interview with AYO on YouTube, two experienced costume designers who worked on Red Velvet – Irene & Seulgi‘s “Monster” discussed their viral outfits, the members’ incredible bodies, and whether the looks are really underwear.

Lingerie Han CEO Han Seon Mi has been designing costumes for the Korean entertainment industry since she worked on the 2016 movie The Handmaiden. Joined by junior designer Na Hyun Bin, she’s branched out to working with idols over the past five years—including Apink, aespa, and Red Velvet‘s first subunit with Irene and Seulgi.

| AYO 에이요/YouTube

Lingerie Han designed and created some of the most iconic outfits from the “Monster” music video and stage performances. One AYO commenter remarked, “This body and face look belongs to Red Velvet,” and the designers couldn’t disagree. Han Seon Mi excitedly shared that the outfits “went viral” with many comments since Irene and Seulgi wore them. Of course, there’s a lot going on behind the scenes that fans don’t know.

| @hi_sseulgi/Instagram

First off, chief designer Han Seon Mi had something to clarify: despite the business’ name and the style of the outfits, these stage costumes aren’t actual lingerie or underwear.

| AYO 에이요/YouTube

To be precise, the one Irene is wearing is not underwear. It’s just regular clothing.

— Han Seon Mi

The CEO stressed that the “lingerie look” is not the same as wearing actual underwear. She went on to explain some of the differences: lingerie looks are made from different materials to actual underwear, for example. Lingerie look costumes also have higher bustlines so that all sensitive areas are fully covered during shooting.

| KBS K-Pop/YouTube

So it’s okay to wear [these costumes] as an outfit. If you wear a bra with this… Nope. That’s just wearing underwear.

— Han Seon Mi

Of course, Irene and Seulgi’s costumes were based on real lingerie designs. Irene’s outfit, the Lingerie Han head explained, is called a “panier”—also referred to as birdcage or basket lingerie because of its shape.

| SMTOWN/YouTube

Irene’s panier, which doesn’t have a bra cap, is modeled on real, traditional corsets which is why it has a busk—the rigid clasp at the front.

| AYO 에이요/YouTube

Seulgi’s outfit, on the other hand, is called a “bustier” and was made with an inbuilt “bra cap” at the top.

| SMTOWN/YouTube

According to Han Seon Mi, bustiers have a “shapewear line with extreme design” that cinches the body inwards.

| AYO 에이요/YouTube

The CEO went on to show how Seulgi’s outfit had numerous hook-and-eyelet clasps on the back which were covered by her jacket in “Monster”. She revealed every single one was closed tightly “because she’s so thin!”

| AYO 에이요/YouTube

Despite working with so many stars, the Lingerie Han team were wowed by these idols’ body types. “They must not be human,” said Na Hyun Bin.