Complete the indicated task to unlock the corresponding character.

Cruz: Go to the small area near the exit of BF 23. Another exit will appear. Go there and enter BF 23.5 to find Cruz.
Mistel: Search both villages in BF 13 to go to BF 14 I/II and find Mistel.
Pamela: Under the Hard difficulty, go to BF 23 or BF 24 and put Nietzsche next to her.
Russell: Go to BF 20, move left, and save Flone from Aegina. Then, place anyone next to Russell in BF 21.