New aokumashii game released today.
Older brother faps to sister's panties, gets caught but sis lifts skirt and "helps" him finish. More scenes ensue.
Also on English-side
http://www.dlsite.com/maniax/work/=/product_id/RJ209965.html
http://www.dlsite.com/ecchi-eng/work/=/product_id/RE209965.html