- For other forms of Seina, see Seina (disambiguation).
|Real name||Seina Kobayashi-Yuki|
|Age|| 15 (Season 1; Not seen)|
16 (Season 2)
17 (Season 3-4)
|Occupation|| Student of Duel Academy|
Student of an All Girls School (formerly)
|Appearances||Chaos of The Light|
|“|| My brother may not be smart in the learning area, but he excels in the dueling area!|
– Seina Yuki
Seina Yuki is the daughter of Ryuji Yuki and Asami Saito, stepdaughter of Maiko Yuki, and the younger paternal half-sister of Jaden Yuki. She is a first-year Obelisk Blue student of Duel Academy and a former student of an All-Girls School in Tokyo. Seina duels with a "Gem-Knight" deck with her Duel Spirit being "Gem-Merchant".
Seina is very slim with a petite build; she has she has long light brown hair and green eyes. She wears the normal Obelisk Blue girl uniform, but with a pair of shorts underneath.
- Duel Spirit communication: Seina has the power to see and talk to Duel Spirits.
- Dueling proficiency: Seina is a skilled duelist, able to work with anything she has on hand.
- Adaptability: Seina able to quickly adapt and change her current plan if needs are.
- Normal level intelligence: Seina is smart in her own way, and does what she can to turn in her homework on time.
- Not willing to get close: Recently, Seina has begun to distance herself from her brother, reasons unknown to him and everyone else.
- Academy-issued Duel disk
Seina runs a Gem-Knight Deck. Like Jaden, they involve the usage of their own version of Polymerization, Gem-Knight Fusion, to create stronger monsters.
- Seina was originally named Reina
|Season of Chaos series|