Trip Report: Hirakata Park near Osaka, Japan
It's pretty compact, going in and out of itself several times, and coming pretty close to the trees that surround it.
The park generally opens at 10:00, closing at 17:00 or later. They close some days, especially during the off-peak season, so it's important to check the website. Admission with an all-day ride pass is 4400 yen; admission only is 840 yen. If you just want to ride each of the coasters once and do nothing else, it is cheaper to pay per ride (2600 yen plus admission if my math is correct), but if you add a couple re-rides to that list, it's better to just buy the all-day pass.
Access is pretty easy: Take the Keihan Main Line to Hirakatakoen Station and walk south about 5-10 minutes. The park is right next to the tracks and you'll see it on the right if you're coming from Osaka.
Note that the Keihan line doesn't serve Osaka Station; you'll need to transfer in one of various places using the Loop Line or the subway lines if you're coming from somewhere else in Osaka (total time from Osaka Station is under an hour). It also doesn't serve Kyoto Station, passing a little east of it. You can use the Kanasuma Line which becomes the Kintetsu Line to transfer, or cut your fare in half by using the JR Nara Line and transferring at Inari/Fukakusa Station or Tofukuji Station. From Kyoto, it takes about an hour.