The Intro is kinda cursed (not only in this Tab), and not supposed to get played by a Bass (You can play it with a Plectrum, that should do it), but this work for it purpose... qwq.
I would advise to play along with the original う•ウ•う

Introduction: —"number/" eighth note


Intro:
G |——————17/—————————17/——|
D |13/16/——15——13/16/——15—| (x2)  
   1  &  2  &  3  &  4  &

Main:

G |————————————————|—————————16————————|
D |17——17——14——14——|17/16/14/——————————|
A |————————————————|—————————————16——16|
E |————————————————|———————————————————|
    1 & 2 & 3 & 4 &  1 &  2  &   3 &  4 

G |————————————————|16/12/11/16/17——17|
D |17——17——16——16——|——————————————————|
A |————————————————|——————————————————|
E |————————————————|——————————————————| (repeat the whole main part)
    1 & 2 & 3 & 4 &  1  &  2 &  3 &  4 

Intro again:
G |——————17/—————————17/——|
D |13/16/——15——13/16/——15—| (x2)  
   1  &  2  &  3  &  4  &

Now the next version would starts...

This is just the first part :D
The whole think is like 6:30min long... but its nearly always these both melodies in different orders.

I hope I was possible to help you uwu



PS: The Intro is btw also the background melody, so if you have a good friend, he/she can play this through the whole thing with you ;D