My friends like anime way too much . . . they decided that to give me an encoded message, but I can't solve it because I'm not a weeb!
railguns are cool
Since this is a crypto challenge, we first do a quick google search of "railgun cipher"
One of the results mentions something called a "rail fence cipher"
Using rumkin, we can try different rails on the ciphertext.
A rail of 5 gives us railgunsarethebesteasyctfl3v3l5esp3rs
If you didn't want to go click through the rails, googling "misaka mikoto" yields a wikia page, which tells us
She is the third ranked Level 5 esper in Academy City, and is nicknamed the Railgun due to her signature move.
Using this clue we can guess that the rail value is 5
easyctf{l3v3l5esp3rs}