The Strongest Demon is the 44th chapter of Tsubasa: Reservoir Chronicle.
Kurogane is still trying to free Syoaran from the demon strangling him.
Kurogane slices Syaoran's left hand free. Syaoran then uses a lighter to burn the demons arms. He is now free and escapes the room with Kurogane.
The scene reverts back to Fai and Seshirou. Fai says in a friendly tone "Oh, might you be Seshirou-san, the one that taught Syaoran-kun how to fight?". Fai tells Seshirou that he and Syaoran are traveling together. Seshirou says "Traveling across dimensions I assume" "Syaoran doesn't have the power to move between worlds" "That means he made a pact with the Witch of Dimensions, huh?" Fai replies "The same with you" "You seem to have strong powers there..." "Perhaps your ability to travel between worlds is in your right eye?".
Seshirou tells him "You're pretty sharp" "I exchanged my right eye for this ability" Fai asks "However, that eye is restricted in its number of uses, no?" Sehsirou says "That's why I've used this power sparingly" "All for the sake of meeting those two". Seshirou strikes at Fai. Fai tells Mokona not to leave Sakura's side. Fai gets hit in the the leg.
Seshirou says "Your leg hurts doesn't it?" "Maybe you could escape if you used your magic powers..." Fai tells him that he has already decided to not use magic anymore. Seshirou says "Then I guess it can't be helped" "Goodbye". He makes one final blow on Fai.
It goes back to Syaoran and Kurogane. Syaoran says "The demons in this "Dwarf Tower" are supposed to be really strong, maybe the chance of returning is even lower than 7%" "If that's the case, what happened to the demon hunters that didn't return?" "If the demons killed them, there should be human remains here" "But there isn't anything". Kurogane replies "Maybe they ate them" "They would leave bones... if they were alive.." "Let's go".
The two of them move on. Kurogane continues to talk, "Looks like you got used to not seeing". They end up in front of a huge door. Both of then walk through the door and Kurogane tells Syaoran to not let his guard down. There is a small curtain and they hear a voice. A small happy girl comes out and says excitedly "We have customers!" "Welcome!, Welcome! To the Dwarf Tower!" "Sorry for the late introduction, I'm Dwarf Sumomo!" There is another dwarf with her that shows no emotion. She says "I'm Kotoko".
Sumomo continues, "We haven't had customers in a long time! Service! Service!". Kotoko asks "You've come here because you're looking for something correct?". Syaoran tells Kotoko "We want to ask about the Demon Leader". Kotoko says "Since you managed to get here, you two must be very skilled demon hunters" "Alright then, I'll tell you" "The Demon Leader, the one you speak of..." "There isn't any public knowledge of it" "This is 1-1" "This means this is that strongest demon" "The strongest demon is the only one with a human appearance" "Other demons look humanoid, but they only follow this demons order" "Its power is overwhelming" "An 1-1 demon also has an interesting ability for some reason". Syaoran interrupts, "That means it has a hooded cape and has an eye..." Kotoko tells him "Incorrect".
Kotoko says "The one you mentioned only appeared recently, its different". Syaoran tells her "But, the demons were only following his orders". Kotoko continues to say "That is an interferer" "These past few days, the municipality has been tracking him down and plan to eliminate him". Syaoran thinks to himself "This Outo place, what on earth is going on?"
Sumomo interrupts "Emergency! Demons are attacking civilians!" "There are casualties!" "The location is at the cafe, "Cat's Eye!".