In Level 1, Stage 4, head all the way at the end in the first part of the level and walk into the dead end. After that, go all left until you will see a gap. Enter the bush with a black area to find the HAL room. In Level 6, Stage 5, in the 3rd room, go all the way at the end and fly up to the conveyor belts and go into that black area at the top of the conveyor belt. You will go into the cannon room and it will shoot you, and you will see the HAL blocks.
At the end of each level if you land on the 7th, 6th, 5th, 4th, 3rd, 2nd, and 1st floors in that order in the bonus jump game, the jump to the 1st floor at the end will reward you with 30 lives instead of 30 Stars.
Unlock the following bonuses by performing the corresponding tasks:
BONUS - HOW TO UNLOCK Arena Mode - Complete the game once Extra mode - Complete the game once Kirby Master video - Complete both arenas and get %100 on Main and Extra game Play as any character in Arena - Beat Arena once Play as any character in True Arena - Beat True Arena once Sound Test - Complete the game once True Arena - Complete Extra Mode