K-pop singer Taeyeon in a teaser photo for 'Letter To Myself.' Photo from Taeyeon's X accountK-pop diva Taeyeon of Girls' Generation made a comeback on Monday with her sixth extended play (EP) "Letter To Myself," headlined by its title track that the artist personally selected.

In a YouTube livestream, the 35-year-old artist described the six-track EP's single as a rock song with high notes.

"It had been a while since I really belted out high notes. If you had waited for the high notes, then this song is for you," she told fans in the subtitled livestream.

Taeyeon shared that she insisted on choosing "Letter To Myself" as the lead single, despite having differing opinions with her label, SM Entertainment.

"This is the song of my taste, and the title track candidate was another song, and everyone in the company except me liked that song," she recalled during the livestream held from Seoul.

"Everyone voted for the other song, so I thought if I was weird, and I lost confidence. But I have to sing the song, right? So I don't know where I got the confidence but I pushed for this song," she said.

Apart from "Letter To Myself," the EP also includes "Hot Mess," "Blue Eyes," "Strangers," "Blur" and "Disaster."

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Taeyeon said the music video and accompanying photos for the record were shot in London.

"I love London. But going there for work made it feel different. I had only been there for travel so it was my first time going there for work," she said.

"Letter To Myself" follows "Heaven," a single which Taeyeon released in July.

The singer, whose full name is Kim Tae-yeon, debuted in 2007 as a member of Girls' Generation, one of K-pop's most iconic girl groups, known for hits like "Into the New World," "Gee," and "Genie."

Outside of the group, Taeyeon has established a successful solo career, yielding singles such as "I," "Rain," "11:11," and "Fine."