Skyliner round tiket

Hi, I'm thinking to by a round ticket, I'm going to spend 3 weeks in Japan
My question is if The round ticket is valid for this 3 weeks or I have to buy 2 one way ticket, and if I have to book in narita back tiket,.
Thanks a lot

if The round ticket is valid for this 3 weeks or I have to buy 2 one way ticket, and if I have to book in narita back tiket,.

Yes it is valid for 6 month from the purchase.

http://www.japan-guide.com/forum/quereadisplay.html?0+149968

Though I can not find the definite information about the reservation for the return travel (to Narita airport), I believe you can make it whenever you like at the Keisei train stations. Maybe someone will write more accurate information.

Correct, you can make the reservation for the return whenever you like at a Keisei office. When you purchase the return ticket you'll get a ticket that you hand over when making that reservation. They also give you a timetable.

Note that you can order it online at a slightly reduced cost and pick up the tickets from the counter. http://www.keisei.co.jp/keisei/tetudou/skyliner/e-ticket/en/ticket/sky...