It's not a doujin, it's an eromanga by Ogawa Kanran. I forget which book.
hau-I turn on Sis's computer and go surfing for porn sitesWow... this girl... she's totally naked... right in the middle of the street...*shiver*hhhffnn*shake**tense**slide**grind**clunk**squish**rattle**squish*haaDon't look at Hana's boobs*rattle*khn-Ha~!*rattle**rattle**shiver*ahn-kya...uhhkh-*shiver*au~~hhhhu-kh*shiver**rattle**rattle*I'm skipping school again today*twitch*ah*squish**rattle*After Dad's gone to work, and Sis's gone to school, around the time when Mom starts hanging out the laundry to dryI finally wake upAne-imouto (part 1)Then I play with myself while looking at stuff like pics of naked girlsNo... no... don't look...Aah~! My clitoris- feels good-*squish**yawn*haa*shake**twitch*why is it so good-