Ever heard of Takaya by Yujiro Sakamoto,
Well, Me either until I saw this 'infamous' ending along with some mention of the series and according to the description from baku update and my anime list,Also did you know some of the art is a bit ugly :
Homura Takaya parents went bankrupt and received a large sum of money from their neighbor, the Shirakawas, one the worlds most distinguished and richest family. The only condition is that Takaya will go to the same school that his childhood friends, Shirakawa Nagisa and her older brother Shou, attends. But this is no ordinary school. Only strong people are in this school and their only rule is "power". Being slightly below average, Takaya must train himself to stay alive in this school.The series ran from Weekly shonen jump from 2005 to 2006 and it comes in two arcs and also has a pilot chapter from WSJ no.35 (2004):
1) おとなりさんパニック!! –which means Neighbors panic!!:It was a pilot chapter from WSJ no.35 (2004) and is also printed in vol 1 of the regular series,It earned a golden future cup.
2) 閃武学園激闘伝- which means gakuen fight stage or school fight stage: Starting from WSJ no.25 (2005) to no. 12 (2006) This is a regular arc which involves the protagonist fight against various opponents in various tournaments to survive and reach to the top. It was collected in 5 Tankōbon under the subtitle Gakuen fight stage.
3) 夜明けの炎刃王 which means Dawn of the Flame blade king is where the series took a genre shift and was considered infamous and controversial where it lead to its cancellation starting from WSJ 13 to 26 (2006) ,It is where the protagonist landed in a fictional world and help his allies who look like his friends back in his world. It was collected in 1 tankobon only under the subtitle "Dawn of the Flame blade king"
The series was cancelled in WSJ 26 (2016) with an infamous ending as shown here:
That ending was parodied in the third episode of Haiyore! Nyaruko-san W
As for the author Yujiro Sakamoto he just stopped making more manga after doing a one shot 突撃!!宇宙撃滅隊!(読切・赤マルジャンプ・2007年WINTER)
Rumor has it that he changed his pen name to Jiro Sakamoto and it is unknown if he was the same person or not.
If want to see the scans of the series see them here (note:they are in chinese):
閃武学園激闘伝 (gakuen fight stage):http://www.dm5.com/manhua-takaya-shanwuxueyuanjidouzhuan/
夜明けの炎刃王 (Dawn of the Flame blade king) :http://www.dm5.com/manhua-takaya-limingzhiyanrenwang/
and if one of the scanlators read this and the scans ,please translate them into english.
Reference Sites about Takaya by Yujiro Sakamoto
http://comicvine.gamespot.com/takaya-senbu-gakuen-gekitoden/4050-92131/object-appearances/4040-91367/https://www.amazon.com/Yuuzirou-Sakamoto/e/B004LUYEAChttps://myanimelist.net/manga/66475/Takaya__Senbu_Gakuen_Gekitoudenhttp://pharaodopazoplus.blogspot.in/p/weekly-shonen-jump-pure-rankings-2006.htmlhttp://pharaodopazoplus.blogspot.in/p/weekly-shonen-jump-pure-rankings-2005.htmlhttps://ja.wikipedia.org/wiki/%E3%82%BF%E3%82%AB%E3%83%A4_-%E9%96%83%E6%AD%A6%E5%AD%A6%E5%9C%92%E6%BF%80%E9%97%98%E4%BC%9D-