I have some good memories of my childhood with anime. Now, I try to re-watch every anime moment that stuck in my brain so much.
I remember how I really amazed when Recca fighting in a tournament (or something like that) and suddenly he call Dragon Koku. Then, an old man, who is the human form of Koku, from audience crowd transforming into a dragon and launch a strong laser beam attack to enemy.
I think this is the first time of Dragon Koku showing his attack.
Please, if you remember what the episode of this moment, let me know.