HUNTA-335 - Brother-approved cuckolding! Giving my seed to my beautiful sister-in-law

The flow is the same for all five. First, there's the 'seed-planting' insertion, which is basically just penetration while the brother watches, followed by sex for the sister-in-law to enjoy. Maybe because they're just there to have fun, everyone except Harua Narumiya at the end finishes with external ejaculation on the second round. Can guys really be that detached and business-like about it?