Full summary, thanks to redon from Arlong Park Forums.
Chapter 1,021: "Demonio".
In the cover, Franky and Señor Pink are crying in a bar with a leopard bartender (that is crying too) while have a drink.
Chapter starts with the battle between Robin and Black Maria, at the point where we left off in the previous chapter. Black Maria comments Robin that her giant form must have consumed lots of energy, Robin says not to worry because this battle will be over soon.
Robin uses a new attack called “Sea Serpent” (Sea Dragon Flower - 海竜花) sending her giant arms slithering like snakes to grab Black Maria's legs. However, Black Maria uses the spiky tip of her weapon to attack Robin's arm. Black Maria then realizes that the damage will hit Robin's main body as well, so she keeps damaging the giant arms to damage Robin.
Black Maria uses the tips of her legs, which have poison needles, to injure the giant arms as well, so Robin has no choice but to retract his arms back to avoid them. At that moment, Black Maria uses a new attack called “Maria Net” (マリア ネット) to launch her spider webs and grabs Robin's giant arms. She then uses another new attack called “Oshizumaria” (Binding Maria - お静マリア) to cross the main arms of Robin's giant body and render her body defenseless.
Black Maria puts on her metal knuckles and starts punching the giant Robin's face with her attack “Oiran Knuckle” (花魁 ナックル). The hits affect the original Robin, who in the end, has to vanish the giant Robin. Then Robin creates 4 giant arms behind Black Maria and tries to grab her but Black Maria uses her technique “Ikitomaria” (Dead End Maria - 行き止マリア) to create a wall of spider webs and block Robin's attack.
Next, Black Maria asks her spider to burn the spider webs that she has created in the area. The spider spits fire from its mouth with the technique “Atatamaria” (Flaming Maria - 炎上マリア) and sets the webs on fire, creating a flame wall in the area. Black Maria mocks Robin.
Black Maria: "I think you should try and bloom somethng in this place,
although I think no flower can bloom in the middle of the sea of flames ♥"
As she talks, Black Maria creates spider webs behind Robin, which she sticks to.
Black Maria: "In the end, you couldn't finish this fight quickly as you said ...
You had come to cover Black Leg's failure, and now that you have lost,
you both will just look stupid!! Ufufufufu ♥
Why don't you tell the skeleton to put out the fire again!?"
Brook, who was listening the conversation, answers quickly.
Brook: "What a stupid thing to say, Black Maria-san.
If I were you, I would get away from there as soon as possible...!!
Yohohoho."
Black Maria continues to punch Robin's real body, who is still caught in the net.
Black Maria: "You are merely a tool, Nico Robin!!
Your brain is the only thing valuable you have!!
So you don't need your arms or your legs...
not even your personality!!"
A small flashback begins in which Nico Robin thinks back to the time she was with the Revolutionary Army. Koala and Sabo want to teach her how to fight since they won't be able to protect her after she leaves. Koala offers to teach her the “Gyojin Karate” while Sabo offers to teach her the “Ryuusouken” (Dragon's Claw Fist). Hack arrives and says Koala and Sabo to leave Robin alone since her joint lock is strong enough and she doesn't need protection.
Robin then tells Koala and Sabo that she might want to learn abit about how to use her "palms". Koala and Sabo happily agree to teach her. Robin thinks back to a few times she used her "palms" after timeskip (like when she used her “Gigantesco Mano” on the bottom of the sea to prevent the Sunny from crashing into some rocks) and thinks about how the lessons have been useful. Sabo taught her to look through the “core” of her target and Koala taught her “Gyojin Karate” secret move.
Robin regains her strength and uses a new attack called “Mil Fleur Gyojin Karate: Giganteum” (千紫万紅 魚人空手: 花葱) sending her giant palm to hit the ceiling and creating a shockwave (like “Gyojin Karate” punch) to destroy the entire ceiling. The rubbles that fall down put out the fire and destroy Black Maria's web.
Robin then uses a new technique called “Demonio Fleur” (悪魔咲き) transforming her giant body into a black demon with bat wings, horns and fangs (maybe her body is black because she uses Color of Arms Haki?). Black Maria is shocked and screams.
Black Maria: "Demon!?"
Robin: "I have no problem with becoming a demon.
Since there are people who make me feel needed...!!
And people who willingly rely on me for help!!"
As she speaks, Robin creates more arms around Black Maria to grab her.
Robin: "You said arms and legs aren't needed, right?
“Gran Jacuzzi Clutch” (大渦潮 クラッチ)!!!"
Black Maria: "Aaaaaaaaaah!!!"
In an impressive double page, Nico Robin in her giant demon form clutches Black Maria's body until she is KO'd and bleeding from her mouth. Hearing the screams, Black Maria's subordinates try to see what happens but Brook's created an ice wall so that they cannot pass to the other area of the room. In a small hole in the wall, they see Black Maria unconscious on the ground and Robin's demon form.
Black Maria's subordinates: "Demon!?"
The ice wall begins to break apart, but before Black Maria's subordinates can go to help her, Brook steps in front of them. In another great double page, Brook uses a new attack called “Phrase D'armes Orchestra” (フラーズ ダルム 管弦楽) with which he attacks them with an icy cut in the shape of a G-clef, to defeat them.
Brook grabs Robin, who is injured, while a bird Mary is watching them...
Cut to Tokage Port in Wanokuni. Luffy is eating a month's supply that Caribou stored in his body. The Heart Pirates try to ask Luffy about the situation in Onigashima but Luffy is answering while he's eating, so they don't understand anyting.
Shinobu and Momonosuke have left the group for a moment to talk. Momonosuke is asking Shinobu to do something for him.
Shinobu: "I can't do that!!
If I do it you know there's no reverting back, right?
And your body may change but your heart will remain a child!!!"
Momonosuke: That's OK for me, as long as I have a chance of becoming a bigger dragon!!
Shinobu, please use your “Juku Juku no Jutsu” to turn me into an adult!!!"
End of chapter. Break next week becouse Weekly Shonen Jump magazine will be on holidays (no Jump chapters next week).
