How to get to Hiraizumi from Tokyo
Take the JR Tohoku Shinkansen from Tokyo to Ichinoseki Station (130-150 minutes) and then the JR Tohoku Main Line from Ichinoseki to Hiraizumi (8 minutes). The entire one way trip costs around 12,500 yen and is covered by the Japan Rail Pass and JR East Pass.
Yamabiko trains along the Tohoku Shinkansen travel directly from Tokyo to Ichinoseki Station in about 2.5 hours, but you may be able to save about 20 minutes by taking a faster Hayabusa train from Tokyo to Sendai and transfer to a Yamabiko train there. Note that seat reservations are mandatory on Hayabusa trains, while Yamabiko trains also carry some unreserved seats.
The Hiraizumi "Run Run" Loop Bus connects Hiraizumi Station with all the sites of interest in central Hiraizumi. It loops every 15-30 minutes from Hiraizumi Station to Motsuji, Chusonji, Takadachi Giekeido and back to the station. One ride costs 150 yen, while a day pass for unlimited rides is available for 400 yen (200 yen on weekends and holidays when bought from the Motsuji parking lot).
In addition, regular buses connect Ichinoseki Station via Hiraizumi Station with Chusonji Temple approximately once per hour and around the year. A separate line, the Keisenkaku-Hiraizumi Line provides access from central Hiraizumi to the more remotely located Takkoku no Iwaya 4-6 times per day (no service during winter).
Hiraizumi is also easily explored by bicycle. A rental shop at Hiraizumi Station charges 500 yen for two hours, 200 yen per additional hour or 1000 yen for the entire day. A second rental shop, a few steps from the station, additionally offers electric bicycles at a slightly higher fee.
A rental car is not necessary for covering Hiraizumi's central attractions, but can be convenient when also visiting more outlying attractions such as Takkoku no Iwaya and the Genbikei and Geibikei Gorges. There is no rental car outlet in central Hiraizumi, but most major companies have outlets around Ichinoseki Station.