After Elena mentioned the word dragon both Tomoe and the struggling monster suddenly stopped. Tomoe stopped because she realised that the monster she was fighting and beating up was actually a legendary dragon. And the dragon stopped after realising that somehow this human was able to identify it.
Even though materialising mana on his body was not an efficient use of mana and was extremely wasteful, this also provided him with a very solid way to hide his appearance from most types of scrutiny. So this dragon had never thought that someone would be able to learn about its true identity.
As soon as the dragon realised that the black mist like magic power covering its body started to disappear. Soon the form of a lizard-like being with shiny black scales was visible before everyone's eyes. Tomoe looked at the being with an amused expression on her face. It was truly a real dragon.