@Solipsist It's me. And yes, it's Thunder and not Lightning. We can talk in length if that's what you wished for, but I'll cut it short.
天雷
Reads Tenrai
This explicitly means Thunder. A little bit of dissect, 天 (ten, ama) means heavens/sky/imperial and 雷 (kaminari/ikazuchi/rai) means...
Guys, guys. Do remember that Murata's version is the official magazine one. Which means, just like Naruto and other shounen manga, money and editor are involved. Murata's drawn-out pacing could very well be the result of the editor's wish.