To change the annoying font in Neo Steam, you must go to the font directory in the folder you installed the client into. It appears in the 'Data\FONT' directory.
Open the define.ini file
Disclaimer: Use under own will! Works on Gamigo client. Hadn't tested on the NA Atlus or Ijji client.
[Font]
;File`s name for chatting(file name in 'Data/Font'. like consola.ttf)
BaseFile=
;File`s name for big font(file name in 'Data/Font'. like consola.ttf)
TitleFile=
;font name(if font is base of windows, write just font name)
BaseFont=consola
TitleFont=consola