Shoma Yusa is the protagonist of the Yu-Gi-Oh! OCG Structures manga series.
He is a soft-spoken and shy boy who only recently moved to the big city at the invitation of his older sister Ageha, but is more than ready to throw himself into the card game he loves.
Just like every other protagonist, his name also contains "Yu" in it, except it's placed within his surname similar to Jaden Yuki.
By touching a Deck Shoma instantly gains all information on a card's effect within the Deck. He can enter that Deck's Struct World and communicate with the Duel Monsters who reside there.
Shoma initially used to live deep in the countryside where he would have to wait at least a week to get the latest OCG packs. The only person he could duel with was his older sister until three years prior when she moved to Tokyo for a job. During that time, Shoma collected a lot of decks but could only play against himself.
Recently, just as Shoma was about to start middle school, his sister announced to him that she would be moving close to the Satellite Shop (a Yu-Gi-Oh! specialty store) and offered Shoma to come live with her in Tokyo which he agreed.
Ageha is Shoma's older sister who played Duel Monsters with him for most of his early childhood until she moved away. When she moved closer to a store center around the aforementioned card game, she offered Shoma to live with her so he could play with others instead of all by himself.
Goriki Jukyu (Strong Jukyu)
Jukyu was the first person Shoma dueled in three years when they met at the Satellite Shop. After their duel the two insistently became close friends who often play against each other for fun.
Yami Kuroda (Dark Kuroda)
Kuroda is a schoolmate of Shoma who instantly took a disliking to him for talking to his sister and challenged him to a duel. Kuroda's reasons for this is due to him being overprotective of his sister and believing Shoma was hitting on her. After Shoma defeated him, he was able to earn Kuroda's respect and friendship when Shoma took an interest in his summoning chants and special moves.
Tsukiko Kuroda (Light Tsukiko)
Tsukiko is Dark Kuroda's younger sister. Shoma first met Tsukiko at school when he saw her playing with Duel Monster cards and wanted to request a duel with her but was stopped by her older brother. After her brother lost to Shoma, she took an interest in him and wanted to duel him next, thus becoming friends.
Shoma uses a variety of Decks, which he often switches when facing a new opponent.
His first Deck is a Tenyi Deck, which incorporates negating strategies to clear his opponent's field effectively. It gives him an advantage to deal with strong monsters before taking his opponent on. It has been enhanced with Yang Zing monsters to support Synchro Summons, before upgrading it with the titanious "Draco Berserker of the Tenyi".
He later switches this Deck for FIRE Warrior one, which focuses on using Equip Spell Cards to power his monsters up, as well to bring out his star monster - "Immortal Phoenix Gearfried". He also adds some Level 9 monsters for Xyz Summon.
Using the retro "Gaia The Fierce Knight", Shoma's tactics have adapted for Fusion Summons. Generally it is about quickly bringing out the materials to overpower his opponent with the majestic "Gaia the Magical Knight of Dragons", a monster that can attack twice and gain ATK as it strikes.