The nearest airport is Shonai Airport, from which shuttle buses run to Tsuruoka (30 minutes, ¥740).
Tsuruoka is on the JR Uetsu Line which runs along the Sea of Japan. The Nihonkai night train passes through Tsuruoka -- its southern terminus is [wiki=0d70a380fe641d8206c6d43c185b9c23]Osaka[/wiki], and its northern terminus is [wiki=157e0bc725227811a9a89993dab2be42]Aomori[/wiki].
From [wiki=62413a57c5e3dc51177995fa175d3286]Tokyo[/wiki], Tsuruoka is reachable in as little as four hours by taking a Joetsu Shinkansen Toki or Max Toki service, changing in [wiki=2973c7fc35d4ded7274a2188b8898532]Niigata[/wiki] to one of several daily Inaho limited express trains (¥12,760). Taking local trains from [wiki=62413a57c5e3dc51177995fa175d3286]Tokyo[/wiki] is silly, because the overnight bus is comparable in price and faster.
Shonai Kotsu runs an overnight bus, the "Yuhi Express", from [wiki=c58c2778fa766fdb6b5ee1fe43f3af61]Shibuya[/wiki] and [wiki=159ec059f6aadff9767562ae9581ece5]Ikebukuro[/wiki] in Tokyo to Tsuruoka. It takes about 8 hours from Shibuya to Tsuruoka at a cost of ¥7540 one way, ¥13,570 round trip.