User blog:B214/LN spoilers

Be noted this is a spoiler blog so proceed at your own risk.

Ikki's tournament opponent:
 * 1st round: He was up against the previous champion
 * 2nd round: He was up against the previous runner-up, though he won easily
 * 3rd round: He was up against Sara, who is C-rank normally but becomes A-rank when she uses her greatest ability
 * Semi-final: He was up against Amane, who is A-rank and super lucky
 * Final: He's going up against Stella

(Spoiler from AP24)

Volume 4
 * 1) The founder of Akatsuki is Bakuga Tsukikage (月影 獏牙). He's the current Prime Minister of Japan and his goal is to ruin the Seven Stars Sword Art Festival.
 * 2) Ikki met Edelweiss while he was chasing Nagi who kidnapped Shizuku.
 * 3) Edelweiss is a very kind person in contrast to her reputation of the "worst criminal ever", so the reason why she became a criminal is unknown.
 * 4) Ouma defeats Tohka and Stella.
 * 5) Stella asked Nene to give her personal training.
 * 6) Shizuku replaces Nagi as a representative after Nagi gives up her position. Tohka was injured due to her battle against Ouma so she cannot act as a replacement.

(Japanese Wikipedia)

Volume 5
 * Ikki went against his first round opponent, Yudai Moroboshi the previous winner of the Festival.
 * Ouma and Ikki fought in this Volume but Ikki was easily defeated (actually its pwned) by his brother.
 * Ikki defeats Yudai using Blade Steal (Edelweiss) + Ittou Shura/Rasetsu.
 * Stella was almost absent for the entire Volume and only returned at the end of the Volume.

Volume 8
 * 1) Stella's power is revealed to be Dragon related instead of fire related as initially though.
 * 2) Ikki defeats Amane easily (not sure how).
 * 3) Ikki's heart stop beating after the match.
 * 4) Ikki wakes up 1 week(?) later but the tournament should've ended by that time, but didn't because of the support Ikki has gained so the finals was postponed.
 * 5) Ikki managed to beat the previous champion thanks to his accidental encounter with Edelweiss. (In short he somehow copied her sword technique.)

Spoiler regarding Sara, Volume 7
 * She is hardcore fathercon. She is actually a world famous painter. She need Ikki's nude body in order to completed her and her father's greatest master piece and also she already get a permission and support from Stella to draw Ikki's naked body in exchange for her painting in the future.
 * Sara's father is already dead because he is to absorbed in creating a single master piece. In the beginning she hates drawing but started to draw more and more because she searched for a connection and bonding in order to understand her father.
 * The drawing that Sara promised for Stella is a drawing of herself and Ikki in a wedding dress for the royal palace portrait in the future if Ikki and Stella got married.
 * For Sara, Ikki's body=ideal body for men. She said to Stella that she doesn't have any feeling of love toward Ikki and even said that Stella and Ikki is perfect for each other and compliment her in order to get her to let Ikki be her model + the promised painting of a famous painter and Stella also can look at Ikki's nude body made her side with Sara despite Ikki's objection in this matter. Sara and Stella the chase after Ikki for whole night until Ikki hide in his brother's room.

Then a bit of Ouma, Volume 7.
 * Ikki apparently talked with his brother first to hide him in his room and explained the situation to him. He accepted with the condition of only 1 night and sheltered him. In there thay have a conversation as a sibling. In there we can truly see that they are sibling after all. In my opinion, they just like a normal sibling with a bad relationship. Ikki protest about him joined hand with a terrorist like group (akatsuki) and ouma just said that he was asked by their father to do this. Ikki just glad that he is still the same stoic brother whose purpose is only to be the strongest. Ouma also give the reason why he should stay away from Stella, he want Stella to see that there are more stronger people out there and want her to grow.
 * Ouma only wish is to fight a opponent that can make him go past his limit. Because Stella is stronger now, he doesn't have any kind of protest to their relationship anymore. Seeing Stella power he eagerly want to fight with her.

(Spoilers from runset)