Inuyasha VS Blood Lad-that you didn't noticed!

You never noticed there are many things in common about these two animes and it's freaking me out! Actually, it's been a long time since I noticed.

 

Ah, forget it! Read it and you'll know what I meant. Inuyasha and Staz share almost same personality. They met a human girl in first episode, Fuyumi and Kagome. They also have an older brother which they hated very much. The rest you can read as above.

What happened? Was it a coincidence? Was it purposely done by Kodama-san? Will we ever know?