いつの間にかムッチムチだった妹とグチョグチョ（Itsu no Ma ni ka Mucchimuchi Datta Imouto to Guchogucho）

She's lost the baby fat but still oh so soft...
oniichan slips his throbber into loli's special place
so it goes "gucho-gucho" ~

[From DLsite English]