His age is 22 in Korea due to East Asian age reckoning where a newborn baby is 1 year old already.
Despite his international age being 21, the English translation of the story events in-game still has his age stated as 22 years old. This also applies to other characters.
Seven attended college and graduated early. In Yoosung's route, he claimed to have graduated in a year and a half and to have attended an Ivy League university.
Seven's phone number is +82)10-7070-&O&X
707 flipped upside-down is 'LOL', with his online name possibly referencing his tendency to say 'lol'.
As a secret agent, he works under the codename "707 EXTREME".
Seven's baptismal name, "Luciel" (which he later legally changed his name to) was chosen by him as a reference to Lucifers Angel name before falling with intentions of having a life that will not end up as the fallen angel. He did this so that every time he heard that name it would remind him not to become like his parents and to keep his promise of protecting Saeran. "If Luciel gets a happy ending... then it'll be a history changing miracle."
Seven underwent physical training as part of his training as a secret agent (which Seven mentions when Saeran breaks into Rika's apartment and meets MC and Seven arrives to Rika's apartment after to save MC). He also presumably is trained in the use of firearms (as he kept a gun in his car, seen during the Secret Ending). Also, in Rays route, he usually keeps a gun on him. However, Seven states that his not very fit but in V's route, Jaehee is amazed by how muscular Seven's arms are. He can also run very fast.
Vanderwood mentions that when Seven was a college student, he always worked at night and slept less than 3 hours every day. 
He also said that Seven is always a kind of a monster, but was way worse before since he was an OCD perfectionist, which surprised Jaehee since he tends to leaves crumbs and soda cans all over his house. His attitude was apparently changed after he received a floppy disk from Rika, although Vanderwood never knew what was inside the disk nor the sender.
According to a phone call, he finds bugs gross but has no problems running to kill them, this probably has something to do with his brother being scared enough of bugs that he would start crying too just like MC did on the phone.
According to the RFA Orientation Guidebook:
His email is email@example.com
His special talents include hacking, infiltrating, and being fluent in 18 languages.
His most used apps are his self-developed wiretap sensing app, calculator, UTube, FB, Tripter, and the RFA Messenger.
He desires a new racing car, a day without work, and a cat robot with excellent artificial intelligence.
His favorite quote is: "It's not that people have humor. Humor is what moves people."
He doesn't limit his preferences only to female as long as he or she shares the same sensibility as him.
According to Cheritz they implied that it wasn't meant to be sexual. They wanted players to know that they are all treasured no matter their gender. They haven't made any statements regarding his sexuality of whether he is pansexual or bisexual.
With the person he likes, he would like to take her on a drive along the beach in one of his cars.
He can't imagine having any other job besides being a hacker.
He claims to be in a love triangle with Grome and Hindow (programming languages or programs).
When he has a difficulty coding, he has a habit of loudly tapping his mouse with his thumb in a rhythm.
Seven refers to V as his “big daddy” once in the game.
He says his first date with his future girlfriend would be on msg.cheritz.com
He would gift his date with something he made himself. He's currently considering a computer program that would make hearts fall from the screen.
Seven tends to break the 4th wall more than any other character in the game.
In the prologue chat, if MC chooses "But I'm not a girl" after Seven hacks through her phone (and sees her face), Seven will reply with "then why do you play this game?" (Yoosung's comment "for ladies" is just the company's marketing strategy.)
In Day 10 of Jaehee's route, he stated at a phone call that he cannot believe that the MC would choose Jaehee's route.
When he first encounters Unknown in Yoosung's route, he said, "oh! the first NPC!".
On Day 2 at 00:00 chat on the Deep Story route, if the player choose to answer with "What the hell's wrong with the options?;;", Seven will respond with, "Perhaps they've been working late? The ppl who made this haha."
At one point in the chat he'll say "If I typed like that though. It'd seem like selecting one of the options in the visual novel. And we'd pass right through it."
He references the reset multiple times.
He also often said "Don't play this game until late at night."
707 has said in Day 5 of Jaehee's route; "A visual novel gives you at least two options, but being a slave in money gives u one option". The player may then respond with a fourth wall breakage as well, this one being, "This game isn't a visual novel, but it gives you more than two options." Seven will pretend he has no idea what you're talking about.
In one of his "The Spaceship Reveals" it says 'The main character is always faced with a tragedy"
In Yoosung's route on day 7 Seven says to Zen Don't talk about your past in the Yoosung's route.
During the Christmas event on (??) You may choose the option "Seven, activate your Yandere mode!!" He will respond with "I knew you would choose that option lolololol"
Ph D. Pepper is actually spoken as "Doctor Pepper", but probably was written as Ph D. Pepper to avoid copyright.
In recent updates, "Ph D. Pepper" has been changed to "Doctor Pepper".
His "love" for cats has inspired him to create a CatBot for MC, with the personality of "707" in the chat room.
He also created his own GPS with a cat voice.
He wants to get married at a space station.
In Jaehee's route, it is shown that he put his car keys behind the car plate, which was easily guessed by Jumin.
In a call with Yoosung, it is mentioned that Seven is an S, which stands for sadist.
Seven himself also stated that he will tease MC in 'sadistic' ways in a phone call.
In a chat room, where after Seven talks about his love for Jumin's Elizabeth the 3rd, he then jokes "My heart is full of love and peace!", "Why can't anyone recognize the love inside of me?" Jumin replies after, saying "If that's love, then you're a sadist." Seven says "What's that?" and Jumin says "Don't ask. You know already."
He is a huge fan of a show called "Mister Chef" and its owner Grandpa Lamsay. They are parodies of "Master Chef" and famous chef Gordon Ramsay, respectively.
When he has time off work, occasionally he plays LOLOL under the username "Hacker God", and claims to be #1 player on the game's Shooting Star server. However, he states that he gets bored quickly playing games, and would rather make them.
When Seven was pranking Yoosung by telling him that he was going to pass out after drinking coffee from "Pass Out After Drinking Caffeine Syndrome", he sends an image of a Wikipedia page in the chat. If the player reads the text, they come across "00000111 00000000 00000111" twice, which translates to "707" from binary.
Seven has stated that he does not drink coffee or alcohol, nor does he smoke. 
In a phone call , Seven states that because he is one of the smallest agents at his agency, he is often forced to play the part of the woman.
Seven is thought to be considered as the endgame -- meaning that he would be the one who is meant to end up with the MC.
The opening song's lyrics supposedly refers to 707's feelings (about MC). The 7th episode of the Secret Route 2 also shows an ending song using "Mysterious Messenger", with a collection of certain images used in Seven's route.
His Good Ending cannot be exactly considered as a true ending for him, as his story (as well as the story's truth) is expanded through the Secret Routes, and Secret Routes are only accessible after the player gets his Good Ending.
In the Secret Routes, the MC's position is Seven's girlfriend.
The opening hints that Seven never really finds out MC's name, and possibly never even did a full check in her privacy.
The main menu screen changes to an image of Seven in both the v1.5.0a and 1.5.1i update.
Seven interfered with Sherlocking's investigations on multiple occasions. He had hacked into all the evidences that Sherlocking has collected and send them off to his agency. 
Seven's first time to use a computer when he was 13 years old (14 by Korean Age).
In April Fool's DLC, his login id and password of the messenger are '707' and 'ga!axyStar$xo' respectively. 
Seven has known both V and Rika for over 10 years. 
The client Seven worked with in his route is code named "G-RACE 64," and he worked with this client for 3 months. 
If you listen to the game's lyrics, it refers to 707 and MC. And the lyrics also mentioned "I've been watching from the start, meaning that Seven is the first one who noticed the player in the chatroom.
At Seven's Route, he was ignoring the player not because he doesn't like her, but he believes that staying away from her is for her own good. (In short, he thinks that he is a dangerous person.)
In Another Story during a conversation with Vanderwood, it is revealed the contact names of the RFA members in Seven's phone. Jumin is "Elly's mom", Zen is "My SafeVault Zen -30k for a selfie", Jaehee is "Assistant Jaehee Kang (Beware of being hurled), and Yoosung is "Superman Yoosung".
According to Vanderwood, he codes with his toes, and named it as Toe Coding.
According to Saeran's Diary:
According to Rika's Scrapbook:
Rika thinks he is needed for RFA-exclusive application, emailing system, and security.
At the age of 19 aliased Chilyoung Choi, he went missing during a dorm party of American University. After two days, it was revealed that he was never enrolled since the beginning from the admission records. His classmates testified that he went through the same housing processes and checked his GPA through the university's official student website. The police noticed, in addition, that they could not find a single lock of hair or fingerprint in his room even supported by forensic examinations.
Seven's belongings: smartphone 1, laptop, gaming mouse, headphones, Ph. D. Pepper, car key, pocket knife, USB(flash drive), second battery, pistol with a yellow ribbon and hand grenade(maybe toy or real), and smartphone 2, 3, 4, and 5.