The date was picked by 紗々目ユキ on Pixiv because of date reading in Japanese - numbers 1-2-9 can be read as "hi-fuu-ku", similar to "Hifuu Kurabu", meaning Secret Sealing Club.
Event on Booth.
A doujin convention that's held bi-yearly in Intex Osaka.
Takes place on Taiwan.
Music Media-Mix Market, or M3, is a bi-annual flea market for independent music makers to sell their goods.
A DJ event held in XENON, Sapporo.
Touhou online convention held on Reddit platform.
A doujin convention held in the Sunshine City complex in Ikebukuro.
A Rumia-only event.
A series of concerts.
Touhou-only event in Kanazawa, Ishikawa prefecture.
Touhou only event held in Shanghai.
Komeiji sisters only event.
Touhou-only event related to Secret Sealing Club.
A Touhou only event that takes place in Kyuushuu.
The Touhou-only event hold bi-yearly in Hiroshima.
A Touhou-only even that takes place in Toki Messe in Niigata.
Concert series in 2018.
Concert series that takes place in Ruido R4 in Shinjuku, Tokyo.
Concert series organized by 歌恋人.
Touhou only event hold in Kyushu.
Main Touhou-only event in Tokyo which hold other events, like:
It's also an event for circles that are selling their goods unrelated to any events listed above.
A event that helds many minor Touhou-only events at the same time.
Touhou-only doujin event that takes place in Nagoya.
The Touhou-only event in Kawasaki.
Club events in MILULARI, Osaka.
A Touhou-only event, a part of 杜の奇跡 (Mori no Kiseki) event.
A Touhou-only event in Hiroshima. The name "Yarinsai" comes from spelling of "Yarinasai" in Hiroshima dialect.
Mystia Lorelei-only event being held in Kyoto.
Touhou-only event in Numazu, Shizuoka Prefecture.
Scarlet sisters only event.
DJ events featuring anime and Vocaloid songs along with Touhou music in Iwaki, Fukushima Prefecture.
Mount of Faith only event.
Touhou-only event in Kanazawa, Ishikawa Prefecture.
A Forbidden Scrollery-only event.
Club events organised in Nagomix, Shibuya, Tokyo.