Defeat the black dragon in that and recieve the DRAGON TUSK as your prize. When you get there you should sometime get invited to the August invitational. Defeat that dragon and get up to A class as fast as you can.
MONSTER RANCHER GAMES PRODUCE NAGA TRIAL
There is a battle called the Trial Cup in the 4th week of April. That may be a good way to "unspoil" your monster if your style is "GENTLE" or "SPOIL". Note: Your raising style will turn VERY strict if you do this a lot. Every time you return to the Ranch, your monster's loyalty should increase by 5! Simply take your monster back and forth between the Town and Ranch and check your monster's data at each stop. It's very hard to fight when your monster's loyalty level is low, but you can easily increase it. Be warned: this monster is extremely lazy. It will say the combination will create an Asfar or a Boxer, but because of the magic banana it will create an ape. After you've spoiled two of them, freeze them both, the combine them with the magic banana.
The easiest way to spoil them is give them meat each month and let them rest all month. Once you have it you now need to have two spoiled monsters. Have your monster check it out and eventually you'll find the banana. In the jungle, look for the place where the kings once lived. To get the ape you need a magic banana which can be found in an adventure with Karn in the jungle.