I'm researching the birth dates of Mauve characters

- Satoshi (January 9th) : Quiz Day/Tonchi Day (クイズの日 / とんちの日), Cold Day (風邪の日)

- Rion (Februray 15th) : "First spring breeze is named" day (春一番名づけの日), Nirvana Day

- Rikka (March 13th) : Sandwich Day, Shinsengumi Day (新選組の日)

- Justin (March 16th) : World Voice Day, Save the Elephant Day, Donate Life Blue and Green Day

- Erika (April 23rd) : World Book Day, Japanese Children's Reading Day (子ども読書の日), St. Jordi Day, Craft Beer Day

- Ukyo (April 29th) Showa Day (also Showa Hirohito birthday), Tatami Day, International Dance Day

- Hiyori (May 25th) : Africa Day (Peace and Freedom), Japan's First Train Carriage Food Day (食堂車の日), Housewife's Day Off

- Kotori (June 7th) : World Food Safety Day

- Mayu (July 24th) : Tequila Day, Cousins Day, Amelia Earhart Day

- Misaki (August 31st) : "I Love You" Day, Vegetable Day, International Homework Day

- Hitomi (September 5th) : International Charity Day, Japanese Clean Coal Day (石炭の日)

- Hiruto (September 6th) : Magatama Day, Black Day (黒の日)

- Kanna (October 1st) : International Coffee Day, World Vegetarian Day, Sake Day, Glasses Day

- Shinano (November 22nd) : Good's Couple Day (いい夫婦の日), Japan Carpenter's Day, Nagano Prefecture Apple Day (長野県りんごの日), Humane Society Anniversary Day, International Survivors of Suicide Loss Day

- Tomoe (Decemer 26th) : Professional Baseball Birthday/Giants Day (プロ野球誕生の日 / ジャイアンツの日), Boxing Day, National Thank-You Note Day, Saint Stephen's Day

Unrelated :

!Miyuki's official birth date hasn't been revealed, but it's highly likely he was born in March, as Purple Day (紫の日) is March 26th, Mauve Day (モーブの日) is March 17th. Or November 11th according to otanjoubi. jp!<

Fact 1 : Showa Hirohito is a considered one of the most controversial figures in modern history

Fact 2 (by netlab. click) : Good's Couple Day and Nagano Prefecture Apple Day can be likened to Adam and Eve, the first human couple, and their expulsion from the Garden of Eden after eating the apple

(I just realized that besides me, nobody else is posting anything on this subreddit, but I'll still post anyway. Also I tend to use a lot of parentheses when writing, so it might be a little hard to understand)