The lamb in the Unicorn Woods can become inaccessible, and you will be unable to complete your collection.

This bug is one of the more frustrating problems that players can encounter in Suikoden II. After collecting Yuzu's three lost sheep and recruiting her, you should find another sheep wandering the clearing two screens into the Unicorn Woods. When you run afoul of this bug, the lamb becomes impossible to acquire.

In this case, the bug has been properly attributed for a long time. The lost lamb shares a "treasure acquired" flag with the first chest in the Unicorn Woods. The one immediately north of the entrance from Kobold Village. The chest only contains a necklace, so it is easy to avoid the temptation to take it, if you know about the conflict. One byte is allocated to the Unicorn Woods, and it breaks down as follows.

• Bit 0: The Necklace chest on the third screen from the village.
• Bit 1: The Necklace chest on the first screen from the village, in the northwest corner.
• Bit 2: The Necklace chest on the first screen from the village, in the southwest corner.
• Bit 3: The Necklace chest on the first screen from the village, north from the entrance OR the lamb.
• Bit 4: Mangosh.
• Bit 5: Guard Ring.

The actual problem resides in /CDROM/080_ARH/VH10.BIN. Every treasure that can be obtained in the Woods is defined in this file, along with a mask used for setting its bit in its flag byte. There is also a "hotspot" definition that contains the same mask, that is used for determining if the chest should be open, or the lamb should be absent, etc. Konami just happened to use 0x08 as the mask value for both the Lamb and the conflicting chest.

Since the upper two bits of the byte are left completely unmolested, the game can safely be modified to set and check one of them for the lamb. To do this, the mask value in both the hotspot and the treasure entry for the lamb must be changed from 0x08 to 0x40.