is this an official english translation or unofficial?

unofficial most likely

The official is on Webt00n. Though for better experience, fan translations(Flame Comics Scan) are the way to go since they stay true to the original story/novel. ε=ε=(ノ≧∇≦)ノ

Trust me, the webt00n's version makes me disappointed. A reason why I don't upload the official to here. (〜￣△￣)〜