East Japan Railway Co. said Monday it aims to fully resume around April 20 its high-speed shinkansen train services that were disrupted in the wake of a powerful earthquake that hit northeastern Japan last week and caused one bullet train to derail. The operator, known as JR East, said it is continuing efforts to resume full operations of the Tohoku Shinkansen bullet trains connecting Tokyo and the northeast region, after halting services between Nasushiobara Station in Tochigi Prefecture and Morioka Station in Iwate Prefecture following the quake late Wednesday. JR East said it has so far con…