First imagesset from the series. Images collected from mugi, gelbooru, danbooru, rule 34 and pixiv. Current as of December 292013. Feel free to update with new images or higher quality images.

Please note I am sponsoring bounties for dojins from this series.

Oh, and enjoy this: http://fapservice.com/2013/09/18/the-complete-fanservice-compilation-compendium/fapservice.com/2013/12/16/sekai-de-ichiban-tsuyoku-naritai-bd-vol-1-fanservice-compilation/

the main characters hair color seems to change with each pic, is it black or purple? still great gallery.

Base +11, izwansafire +5, Red of EHCOVE +60

wow! awesome artist! very good skill, style, anatomy

Base +6, izwansafire +5, nhoxbaogmail +1

Great gallery! Nice to see most of the (too) few images there are of this series all together.
I hope you'll update when you find more.

Main Chara's hair colour: In the pics that seem official ones (eg 7, 9, 81, 82) it's blueish purpleish.
In some of those 'black hair' pics the opponent seems to be a mix of 2 characters/fights as well (Rio, the silverhaired one and Elena, the redhead) But still, minor issues :)

Base +6, izwansafire +5, Red of EHCOVE +60

wrestling females are pretty hot.

Base +6, Slagathorex473 +2

nice fantastic

Base +5, Red of EHCOVE +60

Pic number 25 whats the name of the manga comic its from?

Base +6, thegrandgee +7