Python 2, 51 49 45 42 bytes

lambda x:"".join(`ord(i)+4`[1:]for i in x) 

Try it online!

Golfed to 49 bytes because .join will accept generators too

Golfed to 45 bytes because of lambdas

Golfed to 42 bytes because of switching to Python 2 and using `` (repr)

Python 2, 51 49 45 42 bytes

lambda x:"".join(`ord(i)+4`[1:]for i in x) 

Try it online!

Golfed to 49 bytes because .join will accept generators too

Golfed to 45 bytes because of lambdas

Golfed to 42 bytes because of switching to Python 2 and using `` (repr)

EXPLANATION:

Uses the trick in the 05AB1E answer.

lambda x: Declare a lambda accepting the string "".join( Join by the empty string ` Repr (string representation)... ord( Unicode codepoint (A -> 65, a -> 97) i The iterator in the for loop ) + 4 Added by 4 ` [1:] With the first character removed ) for i in x While a char i is in the string x 

#Python - 51 49 bytes

print("".join(str(ord(i)+4)[1:]for i in input()))

Explanation:

str(ord(i)+4)[1:]for i in input() #Called generators in Python. Used the 05AB1E answer trick for this. "".join then combines it all into a string. print() prints out the resulting string. 

Golfed to 49 bytes because .join will accept generators too

Python 2, 51 49 45 42 bytes

lambda x:"".join(`ord(i)+4`[1:]for i in x) 

Try it online!

Golfed to 49 bytes because .join will accept generators too

Golfed to 45 bytes because of lambdas

Golfed to 42 bytes because of switching to Python 2 and using `` (repr)

#Python - 51 bytes

print("".join([str(ord(i)+4)[1:]for i in input()]))

Explanation:

str(ord(i)+4)[1:]for i in input() #Called generators in Python. Used the 05AB1E answer trick for this. [] then converts it to an array. "".join then combines it all into an array. print() prints out the resulting string. 

#Python - 51 49 bytes

print("".join(str(ord(i)+4)[1:]for i in input()))

Explanation:

str(ord(i)+4)[1:]for i in input() #Called generators in Python. Used the 05AB1E answer trick for this. "".join then combines it all into a string. print() prints out the resulting string. 

Golfed to 49 bytes because .join will accept generators too