Pyth, 11 bytes

FNwpt++4CNk

Try it! My first go at Pyth.

FNwpt++4CNk
FNw          # For N in w (w is input, N will be single char)
   p         # Print without newline
        CN   # Int with code point `N`
      +4CN   # Add 4 to int with code point N
     ++4CNk  # Add k (empty string), so cast to string
    t++4CNk  # Tail (All but first character)
# Python equivalent:
for N in input():
    print(end='',
       str(ord(N) + 4)[1:])