Ushio Aotski was raised on stories about monsters and demons.  That's probably why he doesn't believe his father when he's told that a beast is trapped in their temple. 

 

While cleaning the temple one day, our young adventurer trips and finds a door in the floor that leads to an underground room (found when he falls through trying to open them).  Ushio is hardly surprised, that is, until he sees the creature in the shadows.

 

A giant tiger monster, the same one from the legends, is pinned to the wall by the Beast Spear.  The creature tries to persuade the boy to release him, of course he would have done a better job if he hadn't threatened to eat him at the same time.  Needless to say, that results in Ushio kicking the handle, driving the spear deeper and freaking out the monster, till he trips and gets slashed at.  Then, he does it AGAIN! 

 

The monster is furious and threatens to eat him, until he sees the youth leaving.  The beast tries to convince him again, but makes the mistake of saying he'll eat Ushio when he's free.  Ushio leaves and tries to cover up the now doorless hole in the ground, before fleeing inside to find his father (who happens to be conveniently away).

Sitting down to painting, Ushio is soon interrupted by his best friends Asako and Mayuko from school.  During Asako's lecture, our young hero to be begins to see weird slimy creatures flowing about in the air.  The girls don't see them and he soon races off to get an explaination from the beast in the celler.

 

The giant monster simply laughs and states that Ushio released his evil energy when he broke the doors.  The fish demons were being drawn to it and would soon grow.  The boy is drawn away when he hears the girls screaming.  Now, they too can see the creatures.  Ushio attacks them with a broom, but soon gives it to Asako and tells her to get inside the house.  Racing back, the youth jumps down into the pit and makes the beast promise to kill the fish demons on the condition that he'll release him.  But, will the creature keep his promise?

 

Ushio pulls out the spear, only to be flung across the room.  The beast states that he doesn't keep a promise to a human.  Ushio is furious and draws upon the power of the spear to transform into Demon Hunter Ushio (the whole long hair and cat eyes, not to mention fighting ability).  The monster dwells on this new event before racing out the pit with his lightning flashing to get away from the spear. 

 

The chase is soon over as the beast agrees to kill the fish demons if Ushio doesn't use the spear.  Ushio attacks, and the monster leaps from the roof and starts blowing up the fish.  The small creatures gather into a huge wormlike red monster.  Demon Hunter Ushio commands the orange monster to help him, and soon they are acting like partners for the first time.

 

After defeating the worm creature, Ushio listens as the Beast Spear speaks to him telepathically.  The tiger monster turns to leave only to find that Ushio demands that he stay.  The beast's evil energy was still there and would attract other monsters for a while.  Ushio knows he'll have to kill the monster someday, while the monster thinks about eating this demon hunter as soon as he gets the chance.

 

The orange furred beast is soon poked in a very sensitive place and turns to glare down at the young teen who is trying to figure out what to call him.  Finally, Ushio settles on the name 'Tora' which means 'Tiger' in Japanese.  The pair bicker about the name until Asako and Mayuko come out (believe it was all a dream).  Tora goes invisible and takes a seat upon Ushio's shoulders, leaving the boy to explain...ok, so he just laughs in embarrisement for being caught talking to himself (or so the girls believe).