Setagaya (Japan) and Yokkaichi (Japan) are 285 km (177 mi) apart in a straight line. The way we suggest is by bus and train, via Tokyo, Shizuoka and Nagoya: about 3h 30m door to door with 3 changes, for ~€24–92 per person. No flight is needed.
Step by step
Bus from Setagaya to Tokyo: about 20m, 7 km, ~€1–2
Train from Tokyo to Shizuoka: about 1h, 142 km, ~€10–45
Train from Shizuoka to Nagoya: about 50m, 136 km, ~€9–40
Train from Nagoya to Yokkaichi: about 35m, 35 km, ~€2–15
Every route we know
Bus + Train, via Tokyo, Shizuoka and Nagoya: about 3h 30m, 3 changes, ~€24–92
Bus + Train + Bus, via Tokyo and Kyoto: about 4h 55m, 2 changes, ~€38–122
Bus + Train, via Tokyo and Osaka: about 4h 55m, 2 changes, ~€40–142
Questions
How long does it take to get from Setagaya to Yokkaichi?
About 3h 30m door to door by bus and train, via Tokyo, Shizuoka and Nagoya, including time for changes.
How much does it cost to travel from Setagaya to Yokkaichi?
~€24–92 per person for the route we suggest. These are estimates from travel-guide prices and published tariffs, not quotes: check the operator for today's fare.
Is there a direct bus from Setagaya to Yokkaichi?
Not that we know of: the routes in our data change via Tokyo, Shizuoka and Nagoya.
Times are rough door-to-door times, with time to change included. We don't have timetables, and fares are rough estimates, not quotes: check Google Maps or the operator before you travel.