The author had so little confidence in Great Teacher Hidaka that they threw away the story and started over? With a story that won't end well for Hidaka? Again?? This retread is extending how pathetic Hidaka was during the original, and there's no charm left when we know Hidaka ends up alone, sad, and boring for years until the first volume.
And I never enjoyed Haruo as a protagonist, so if he's the center of the plot again, for volumes, this feels pointless.
Thanks translator, though. I hope this you enjoy it more than I.