Three more extensions are planned for opening by NUMBER@1 : Hakata-Yatsushiro , PERSON@1 , and by NUMBER@2 : PERSON@2 , and NUMBER@3 : Aomori-Hakodate -LRB- through the Seikan Tunnel -RRB- .

Three more extensions are planned for opening by NUMBER@4 : PERSON@3 , PERSON@2 , and PERSON@1 .
