Aitsu to Ore by TOHJOH Asami

[whey]

Description from Baka-Updates: Takeru’s mother is right about to remarry. That is a great opportunity for Takeru to live with a real family and most of all to have a big brother, Shin. Things do not actually turn out the way he expected though.
A little while before Christmas and waiting for his girlfriend, Takeru hears a couple of people discussing about money for sexual favours. Kind of curious, he turns around to check out the chick, but it happens that both parties are male, and the oddest comes when Takeru realizes that the one prostituting himself is Shin, his new stepbrother…

There's also a book of various doujinshi called Renai Junkie. The fifth story is a spinoff of Aitsu to Ore, called Newly-Wed.

Volume 01
Chapter 01: http://www.sendspace.com/file/50rqtp
Chapter 02: http://www.sendspace.com/file/i6plwq
Chapter 03: http://www.sendspace.com/file/vn1db9
Extra (Shounen S): http://www.sendspace.com/file/20bzqb

Volume 02
Chapter 04: http://www.sendspace.com/file/pxvhh4
Chapter 05: http://www.sendspace.com/file/81aj84
Chapter 06: http://www.sendspace.com/file/vpxfy9
Chapter 07: http://www.sendspace.com/file/huqpwd

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