If you haven't played Mystic Messenger completely, you might read something that will reveal to you the complete story of the game. So please pay attention!
His age is 27 in Korea due to East Asian age reckoning where a newborn baby is 1 year old already.
Despite his international age being 26, the English translation of the story events in-game still has his age stated as 27 years old. This also applies to other characters.
According to the RFA Orientation Guidebook:
His phone number is +82)10-5514-@@@@
His email is firstname.lastname@example.org
His special talent is taking photographs.
He likes simple and convenient pain de campagne (country bread in French), and dislikes nothing in particular.
His most used app is the photo album.
What he desires is a secret.
His favorite quote is: "The bud of our love will swell up during the summer wind, and blossom into a beautiful flower next time we meet."
His occupation is listed as "Jumin Han's chief assistant." (most likely a typo, but continues to exist in the 3rd batch).
His family members are all currently living abroad.
He enjoys jigsaw puzzles in his free time.
When he needs to think, he has a habit of reaching for his smoking pipe.
His ideal type is someone he can feel connected with. He does not believe he will find another person like that.
If he could have another job, he thinks he would still be creating art but in another field.
His first date would be at one of his exhibitions.
He would like to give his date a picture of the sun.
According to Jumin, V has 20 spoons at his home.
It is implied that V's death was covered up as a suicide to Yoosung and Zen to prevent them from knowing about the truth of Saeran having been the one to shoot him.
V was the one who named Elizabeth 3rd.
During the recording session, V's scenes was too sad that both Ho San Lee and the Cheritz staff cried.
According to Jumin, V once called him to leave a will.
In Yoosung's route, Jumin stated V's mother is a composer and his father is a painter.
To fix his blindness, V is required to get eye surgery for a cornea transplant.
In Another Story, Jumin mentions V loves wine and is a heavyweight in regards to alcohol; being able to drink several bottles of wine and still not be drunk.
Jumin implies that the month after Rika's "suicide", V suffered from insomnia.
In terms of music, V is able to sing more high notes than Jumin. This is also the only time V has ever bested Jumin. 
In Christmas DLC, it's stated that V has a bad handwriting, in which Rika didn't like. It is most likely the reason why he is the only person with 'typewritten' font in the character profiles in RFA Orientation Guide book. 
V was never formally trained in photography. His photography skills are all self taught.
V attended university in South Korea while Jumin attended university overseas in either the USA or Europe.
Due to his popularity, Cheritz added a route for V in September 2017 in the new Another Story mode.
The route was originally planned to be released in August 2017.
The route was eventually released on September 9, 2017 in Korea, which is also V's birthday.
Until he met MC, V has never received a hug. He didn't let his mother hug him, and he had always been the giver.