"He was so heroic and powerful with the way he rescued me from those shark monsters. Seeing how he was able to duplicate himself to fight them all was just amazing too! I haven't seen anything like it before! –sigh- Oh OOO-sama."
Also justified for the Bee Yummy, which was spawned from Saji, and thus needed to devour lingerie to grow stronger.
Ascended Fangirl: Hakufu loved to watched superhero anime and read manga while she wasn't training. Her getting a chance to be an actual superhero than just a reincarnated warrior just adds fuel to her already burning Blood Knight fire.
Badass Biker: Just about any Fighter who has a Cell Medal in hand.
Later all of the schools decide to join together in order to fight the Greeed.
Even the Girls Want Her: After being saved by OOO, Ryuubi has now developed an affection for her, even going as far as giving her the nickname "OOO-sama". She has no idea that her fellow king, Hakufu, is underneath the armor.
Expy: Something like that, considering that Ten-Faced and Crome like to use anime characters as Kamen Riders. Aside from Hakufu, they have used Ranma, Keitaro, and many others.
Exact Words: Kougami tells Hakufu that the first meeting of two parties is like a birthday. Of course, with Hakufu being who she is, she thinks that this means that there are a lot of birthdays for her to remember and birthdays that she didn't get invited to or get presents for.
Face of a Thug: Shamoku, the leader of Teikoku Academy, also known as the Barbarian King. In spite of his intimidating appearance, he's very friendly and is a childhood friend of Ryuubi.
Failure Knight: Hakufu, who feels guilty for Koukin being practically sent into a coma with only Ankh keeping him alive.
Fridge Brilliance: "Ikki Tousen" literally means "The sole warrior with the strength of one thousand". And the subtitle is "Medals of Ikki Tousen", though the Medals are used by OOO herself. But either way, the title makes more sense than you think, as OOO possesses more power than any of the Fighters. In other words, OOO is a literal Ikki Tousen.
From Bad to Worse: At the end of Chapter 7, despite their best efforts from all three schools, they only caused Uva to lose one Cell medal. And then he creates two more White Yummies from Chukou and Kakuen to join the Firefly Yummy and the horde of Psuedo-Yummies he had already created.
Funbag Airbag: This happens to Shoichi when trying to escape the Firefly Yummy.
Harsher in Hindsight: "Gameru-chan is so sweet to me. He tries so hard to make me happy. Some days I really doubt if he has desires of his own. I guess that's what makes me so sure he'll never betray me." Although that episode was weeks in the past by the time this chapter was posted, it still applies.
Loophole Abuse: Ankh made a deal with Dr. Maki to keep Hakufu from going after the Cuttlefish Yummy for the next 24 hours in exchange for 1000 cell metals. He then tells Hakufu to tell the other Fighters to go after them, since they weren't involved in the deal.
Mythology Gag: When Hakufu asked Ankh if he was a vampire, he respond that he wasn't a "stain-glassed idiot". Perhaps he met a Fangire once.
Shuutai refers to the Yummies as "Unknown Lifeforms". And the Kamen Rider of this story is being assisted by ordinary humans trained to combat threats. Soundfamiliar?
Older Hero vs. Younger Villain: In reality, the Greeed are a thousand years younger than the ancient warriors that Hakufu and the other Fighters are reincarnated from.
Outside-Context Villain: The Greeed to all the Fighters. Before hand the fighters only had each other to deal with.
Power Copying: The Yummy can can gain qualities from the people they spawn from. Not just speech and intelligence but also the knowledge of martial arts of the victim is a warrior. The Silkworm Yummy which came from Chouhi proved that.