HUNTA-804 "Hey, big brother is already inside!" "I'm almost there, so keep helping me…"

I really love my little sister... She probably doesn't know how I feel, but she still comes to me as carefree and unguarded as ever! And then one day, she insists on taking a bath together and forces her way in, leaving us alone in the cramped bathtub! Naturally, I get an erection and can't get out, and when my sister moves slightly, it accidentally results in real penetration! It's so tight that I'm about to cum, so I say "I'm about to cum soon, help me," and she blushes but nods and starts moving, resulting in raw insemination!