Boktai: The Sun is in Your Hand FAQ/Walkthrough.

By Oscar C

5. Walkthrough

===================================
--------Road of Encounter
===================================
-Items Found: Red Apple
-Boss: -
When you begin, go to the left for an Red Apple and then cross the bridge on the right.

===================================
--------Fog Castle
===================================
-Items Found: Green Apple (x4), Knight Frrame, Solar Nut
-Boss: Count of Groundsoaking Blood

NOTE: This path is best doing it during the day.
Follow the path and then Master Otenko will appear, he'll bring up the Pile Driver (A device used to purify the undead). When Otenko is done talking, continue following the path.

Climb up the steps, then turn left and continue following the path, pick up the Green Apple, then go up and into the next screen, follow the path, you should see a chest, so open it for another Green Apple. Follow the short path grabbing the Solar Nut on the way, and then enter the door.

Go right (you can go to the Otenko panel, but there's no need for it), go through the next door. In this room is a Solar Station (you use these to recharge your weapon), go through one of the rooms - it doesn't matter which one, they both go to the same room anyway.

Go to the right of the room for the Knight Solar Gun Frame, I suggest that you equip it for best results, when your done climb up the stairs. Go to the left and face the box, go up against it and tap a few times, the Bok will start coming after you, quickly run to the right and hide behind one of the boxes (preferably the one below the skylight). When the Bok starts turning, you can either kill it or run away, although running may make it attack you. Go into the next room.

Outside, nothing to do here except to recharge (if needed), so go into the door on the right. Go left for a Life Fruit, then go up the stairs, continue going up the stairs, Otenko will stop you and say that the Immortal is in there, you should save just in case, then go into the door.