Seireki13ya

 (星歴13夜) is an idol group under codomomental formed on December 15, 2018, and debuted on December 25th with a digital single.

Their concept is "今夜のかなた 夜のくに" (Unofficial translation: Night-land, faraway tonight). A unique fictitious constellation is assigned to each member.

Current Members

 * Shiki Towa (色とわ; )
 * Nene Komochi (寝こもち; )
 * Ama Mauru (天まうる; )

Former Members

 * Fuwa Akane (浮あかね; ) (Graduated March 26, 2021)
 * Sono Homare (園ほまれ; ) (Withdrew July 24, 2021)

Style
's overall style is "dreamy/night" as their name roughly translates to "Astral Calendar of the 13 nights". Their music style is upbeat EDM/Eurobeat, with lyrics being yami-kawaii as the rest of codomental's idol groups. While having lyrics as such they are more close to the orthodox idol style, with less yami-kawaii lyrics, cute image, and banning lifting and stage dives.

Their introduction on their site read: English= "Beyond Tonight, Land of Night"

The land of the night that connects this world and that world. Over the thirteen nights are the five star groups of the constellation Amaoto, the Whisperer on a lonely night, the constellation Icosaurus, the constellation Hot Miruku, and the constellation Bedwetting. Even if you count the years, you will probably lose track of which world line you are in. Good night future. 「今夜のかなた 夜のくに」
 * -|Japanese=

こちら世界とあの世界、ちきゅうぼし繋ぐ夜のくに. 13の夜を超えるのは、あまおと座・さみしい夜にささやき座・未明わるいこ座・ほっとみるく座・おねしょ座の5星群. 指折り暦を数えても、きっとどこかわからなくなっちゃう世界線. おやすみ未来.

History
2018= On October 1, there was an announcement of audition to recruit members.

On December 6, the groups visual and the members were shown.

On December 15, they debuted at the "コドモメンタル女子遊戯～たなとす vol,3～" live.

On December 25, they uploaded a pre-debut digital single titled Sekaisengoto.

On January 23, their first single Oyasumi Mirai to Koiotome was released.
 * -|2019=

On March 31, they held their first one-man live at Shibuya Chelsea Hotel titled "Seireki13ya First one-man LIVE ~13 nights~".

On April 21, their second single Itoshi Utakata to was released.

On June 9, a free Mix CD STARRYPOP was given out.

On August 14, their third single Yocto Asterism was released.

On October 13, they held a free one-man live at Tokyo's Shibuya eggman.

On November 27, their first album Hugdreamy Horoscope was released.

On January 25, they held a one-man show at Shinagawa Intercity Hall, Tokyo, titled "Solo Performance ~Starmare Memory~".
 * -|2020=

On January 28, it was announced the group would have their first nationwide tour titled "FemtoNovaSet Tour". It has sadly been heavily affected by the COVID-19 pandemic, but has started up again. To make up for the canceled shows the group has done YouTube Lives to chat with the fans.

On March 18, their fourth single Ai ka Higurashi was released.

On June 17, their fifth single Baby baby Cupid was released.

Albums

 * 1) [2019.11.27] Hugdreamy Horoscope
 * 2) [2021.05.12] MythEpoc

Mini Albums

 * 1) [2021.02.10] Akashic Records (アカシックレコード)

Singles

 * 1) [2019.01.23] Oyasumi Mirai to Koiotome (おやすみ未来と恋乙女)
 * 2) [2019.04.10] Itoshi Utakata to (愛し泡沫ト)
 * 3) [2019.09.15] Yocto Asterism (ヨクトアステリズム)
 * 4) [2020.03.18] Ai ka Higurashi (哀唄日夜)
 * 5) [2020.06.17] Baby baby Cupid
 * 6) [2020.10.21] Romantic Escape

Digital Singles

 * 1) [2018.12.25] Sekaisengoto (せかいせんごと)

Mix CD

 * 1) [2019.06.04] STARRYPOP