Keio tickets

Where and how do i buy keio train tickets from shinjuku to mt takao?

first option in a google search.

https://www.keio.co.jp/english/

click the "tickets" and/or "how to ride" sections.

You can buy the ticket of the Keio line easily at the Keio Shinjuku Station.
Keio shinjuku station is right near to the south exit of JR Shinjuku station.

Buy IC Card "PASMO(or Suica)" easiest and covenient.
1500Y or more than better.(20000Y max deposit 500Y included)
http://www.pasmo.co.jp/en/

fr Shinjuku to Takaosanguchi(end stn)
381Y/IC Card (PASMO/Suica)
390Y/Cash (regular paper ticket)
https://www.keio.co.jp/english/tickets/tickets.html
But also sales discount ticket may better.
https://www.keio.co.jp/english/tickets/discount.htmlhttps://www.keio.c...

Keio Shinjuku stn ticket gates and platforms placed under ground.
https://www.keio.co.jp/english/howto/shinjuku/map.html
http://i.imgur.com/wwYBSye.jpg
https://goo.gl/maps/vunRDwKFCMp
Ticket gate : B1F(Main line/New Line)
Platform : B2F(Main line), B5F(New Line)
Main line stn placed under "Keio department store" building.
http://info.keionet.com.e.bp.hp.transer.com/shinjuku/foreign/en/about....

(note)
Both stns name using same "Shinjuku" be careful searching results meanings.
http://www.hyperdia.com/en/cgi/en/search.html?dep_node=SHINJUKU(NEW%20...
No direct train in daytime fr New Line.
Google MAP using "Shinsen" in JP reading/calling.

typo : (url open error)
But also sales discount ticket may better.
https://www.keio.co.jp/english/tickets/discount.htmlhttps://www.keio.c...

But also sales discount ticket may better.
https://www.keio.co.jp/english/tickets/discount.html https://www.keio.co.jp/english/tickets/takao_roundtrip_keio.html