Incident Resolvers and Twilight Frontier

Realizing that the contact with Earth was inevitable following Operation Kanjuden in year 2015, Yukari Yakumo and Kasen Ibaraki decided to prepare for it by forming Twilight Frontier, a group of Gensokyo Elite Fighters that participated in certain 'key events'. This move was initiated in response of the ever-increasing influence of Yasei Sugaku (who represents the Outsiders) and Iesua Nazarenus (Kaisendou Bloc leader). Following the Reunification in 2020, Twilight Frontier received several additional members following the Perfect Possession Incident and Animal Realm Debacle.

During Jailbreak King Pursuit, Yukari was shocked upon realizing that Yasei was one step ahead of her, as shown by the Outsiders' prompt response once Mizuchi Miyadeguchi managed to possess Fujiwara no Mokou, with the Outsiders leader being a direct eyewitness of the entire thing. At first, the Guards heightened their vigilance, but after Sanae Kochiya ended up being possessed as well, the gloves are off. Many scattered Outsiders then began moving, and it's clear that their movements served a purpose. This also marks the debut of Core Outsiders, led by none other than Yasei himself.

This show of strength from the Outsiders make Yukari realize that she can't approach the initiative she and Kasen made with her usual methods. Following the Reunification, the Incident Resolvers are formally created. Their first proper debut was the Ability Card Incident, where a team consisting of Reimu Hakurei, Marisa Kirisame, Sakuya Izayoi, and Sanae Kochiya joined forces with the Core Outsiders team consisting of Yasei Sugaku, Lucy Thesda, Izayoi Sakamaki, and Iseya Sugaku in finding out the source of the aforementioned Ability Cards. The Resolvers apprehended the culprits while the Outsiders managed to secure Rainbow Dragon Cave to temporarily halt the cards' production.

It's clear that this move was successful, since the Resolvers ended up being deployed several times during crucial events from 2021 to 2035, chief among them was Greater Hell Conflict and Second Dream Incursion. In fact, Prime Core Outsiders was created specifically to serve as the counterpart of the strongest Resolvers. Regardless, it's evident that Core Outsiders already entrenched themselves in Gensokyo, and it's prudent that Twilight Frontier acknowledge this fact. As a proof, Sumireko Usami is a member of both Core Outsiders and Twilight Frontier, with higher position in the former.

Here are the list of Incident Resolvers and Twilight Frontier members. (This list is open for future additions)

Incident Resolvers
- Reimu Hakurei (Reiiden) (2004) (C) [Fugere Gensokyo Squad Guardian]
- Marisa Kirisame (Fuumaroku) (2004) (VC) [Fugere Gensokyo Squad Vanguard]
- Sanae Kochiya (Fuujinroku) (2007) [Moriya Military Brigade General]
- Sakuya Izayoi (Koumakyou) (2004) [Scarlet Defense Army General]
- Youmu Konpaku (Youyoumu) (2004) [Hakugyokurou Hades Operative]
- Reisen Udongein Inaba (Eiyashou) (2006) [Eagle Ravi Corps General]
- Ran Yakumo (Youyoumu) (2006) [Yakumo Clan Shikigamis Administrator]
- Komachi Onozuka (Kaeizuka) (2006) [Ten Kings Ministry Shinigami Leader]
- Rin Kaenbyou (Chireiden) (2012) [Chireiden Kasha Corps Leader]
- Shou Toramaru (Seirensen) (2014) [War God Bishamonten Avatar]
- Mononobe no Futo (Shinreibyou) (2013) [Divine Spirit Mausoleum Shikaisen]
- Alice Margatroid (Kaikidan) (2004) [Rainbow Dolls Legion General]
- Patchouli Knowledge (Koumakyou) (2004) [Voile Defense Corps General]
- Nitori Kawashiro (Fuujinroku) (2007) [GUF Kappa Division General]
- Aya Shameimaru (Kaeizuka) (2006) [Crow Tengu Scouts Leader]

Twilight Frontier
- Yukari Yakumo (Youyoumu) (2004) [Gensokyo Legend Sages Leader]
- Yuyuko Saigyouji (Youyoumu) (2004) [Gensokyo Legend Sages Member]
- Kasen Ibaraki (Shinpiroku) (2015) [Gensokyo Legend Sages Member]
- Okina Matara (Tenkuushou) (2019) [Gensokyo Legend Sages Member]
- Yuuka Kazami (Gensoukyou) (2007) [Gensokyo Legend Sages Member]
- Eirin Yagokoro (Eiyashou) (2006) [Gensokyo Legend Sages Member]
- Eiki Shiki (Kaeizuka) (2006) [Ten Kings Ministry Yama Leader]
- Doremy Sweet (Kanjuden) (2017) [Dream World Ruler]
- Remilia Scarlet (Koumakyou) (2004)
- Flandre Scarlet (Koumakyou) (2011)
- Suika Ibuki (Suimusou) (2004)
- Kaguya Houraisan (Eiyashou) (2007)
- Fujiwara no Mokou (Eiyashou) (2007)
- Kanako Yasaka (Fuujinroku) (2007)
- Suwako Moriya (Fuujinroku) (2007)
- Tenshi Hinanawi (Hisouten) (2008)
- Satori Komeiji (Chireiden) (2012)
- Koishi Komeiji (Chireiden) (2012)
- Utsuho Reiuji (Chireiden) (2009)
- Byakuren Hijiri (Seirensen) (2012)
- Nue Houjuu (Seirensen) (2010)
- Toyosatomimi no Miko (Shinreibyou) (2012)
- Mamizou Futatsuiwa (Shinreibyou) (2013)
- Hata no Kokoro (Shinkirou) (2013)
- Shinmyoumaru Sukuna (Kishinjou) (2015)
- Sumireko Usami (Shinpiroku) (2015)
- Shion Yorigami (Hyouibana) (2017)
- Joon Yorigami (Hyouibana) (2017)
- Yuuma Toutetsu (Gouyoku Ibun) (2019)
- Keine Kamishirasawa (Eiyashou) (2007)
- Medicine Melancholy (Kaeizuka) (2006)
- Iku Nagae (Hisouten) (2008)
- Yuugi Hoshiguma (Chireiden) (2014)
- Ichirin Kumoi (Seirensen) (2013)
- Minamitsu Murasa (Seirensen) (2014)
- Seiga Kaku (Shinreibyou) (2014)
- Lunasa Prismriver (Youyoumu) (2006)
- Merlin Prismriver (Youyoumu) (2006)
- Lyrica Prismriver (Youyoumu) (2006)
- Tewi Inaba (Eiyashou) (2007)
- Momiji Inubashiri (Fuujinroku) (2014)
- Kutaka Niwatari (Kikeijuu) (2019)
- Hong Meiling (Koumakyou) (2004)
- Minoriko Aki (Fuujinroku) (2007)
- Hina Kagiyama (Fuujinroku) (2007)
- Parsee Mizuhashi (Chireiden) (2014)
- Yamame Kurodani (Chireiden) (2014)
- Nazrin (Seirensen) (2014)
- Kogasa Tatara (Seirensen) (2019)
- Chen (Youyoumu) (2006)
- Cirno (Koumakyou) (2006)
- Sunny Milk (Sangetsusei) (2010)
- Luna Child (Sangetsusei) (2010)
- Star Sapphire (Sangetsusei) (2010)
- Rumia (Koumakyou) (2006)
- Lily White (Youyoumu) (2006)
- Koakuma (Koumakyou) (2006)
- Kisume (Chireiden) (2014)