To use the mod, just copy the "DevilKazLaserBeamEffect_P" file into the directory below: Program Files > Steam > steamapps > common > TEKKEN 7 > TekkenGame > Content > Paks > ~mods
Open the game and open the Character Customization Menu for Kazuya, Devil Jin or Kazumi. Then, in the "Effects" section, you need to select the English "KRASH" effect.
For Devil Jin, you can see the new "Boss" laser beam in gameplay.
For Kazuya, you can see it when he transforms to Devil Mode in gameplay. Note that for Kazuya, this mod also includes Boss Devil Kazuya's Chest beam and Wing beams used in his Rage Art. So, optionally, you can use the Tekken Moveset Extractor to load Devil Kazuya's moveset to Kazuya. Better yet, you can download the "STORY" Devil Kazuya Moveset that I have created as one of my moveset mods. It has a plethora of moves and quotes, exclusive to Devil Kazuya Boss in the Final Chapter of Story Mode. The link of the moveset mod of "STORY" Devil Kazuya Moveset is below: tekkenmods.com/mod/982/story-devil-kazuya-double-moveset-mod-pack
For Kazumi, you need to use the Tekken Moveset Extractor and implement the moveset of Devil Kazumi. You can also use a moveset mod that I have created called "TRUE" Devil Kazumi, which has a wide variety of moves from Devil Kazumi, and some other Devil characters alike! The link of the moveset mod of "TRUE" Devil Kazumi is below: tekkenmods.com/mod/856/true-devil-kazumi