Promise to Marry Me When I'm Older!

Seventeen-year old Ryo jokingly promised to marry his six-year old childhood friend Yuka. Ten years later, at the age of 16, Yuka still remembers the promise, but Ryo already has an older girlfriend, Kasumi! This is a slapstick comedy that unfolds as even Kasumi is affected by the innocent and kind Yuka. How will the three people end up..! (Source: YouTube, translated)