When I first played this game, I failed many times. But I found a way to keep trying and break it easily.
It's my walkthrough.
First press the space bar to finish the special "Super Bomb" four times. Gather power-up items as soon as possible. If the power up goes up to its maximum, it's easier to defeat the enemy.
The mini boss is Sky-Chick? I think it looks like Kunoichi ... but when you fight, tip down to the bottom and fight. The final boss, Tsunami Dragon, has fought several times and discovered the attack pattern. Once you are dead, you can hit the spacebar to defeat it.