Ride the Limited Express "Shiosai" on the Soubu Line. Time required one hour and fifty minutes, running generally once every two hours from Tokyo starting from appx. AM7.30. The train fee is ticket 2,210yen and express fee 2,010 yen total 4,220yen (2008.1.1). If you do not use express, time required two hours and 30 minutes requiring only the ticket fee, and a transfer at Chiba Station, running generally once hourly from Choshi.
Other ways of access are via the motorways with your own auto, or highway bus from Hamamatsucho Bus terminal or Tokyo Station Yaesu Exit Bus Station.
The below URL links to the JR train timetable of Choshi Station, week-day schedule. The red times are the Limited Express direct trains bound for Tokyo. Unmarked black times are local trains bound for Chiba Station.
This one-car train links JR Choshi Station to Togawa Station with 10 stations total. It is 6.4 km in length, and each of the station buildings are built to be intentionally charming design, such as Holland windmill, Swiss chalet, Portuguese tiled building, and Japanese 1920's style countryside hut building.