IENFH-043 - Told my sister 'I'll just rub it' but ended up losing control and finishing inside

Brother gets hard seeing his sister sleeping with her panties showing. After getting caught, he expects to be called a pervert, but she feels pity and offers a handjob/blowjob. He can't hold back and lies, 'I'll just rub it,' but the pleasure is too much, leading to a crazy climax where he ends up finishing inside.