You only need one blueprint, then you can forge it as many times as you want. You will need 5 billets though.

How to r5 hamayuni?
Can you get blueprints more than once?

if you're lucky... how lucky are you guys are btw?

F2P rust

to get the blueprint of this, you have to give Takashi mysterious conches everyday for 7 days! I got mine just now :D

I lvled it up to 80 yay

I got the blue print
By the time i get yoimiya ill use this

 Click to Enlarge

I heard this is yoimiyas bow speaking of which in her official art so im preparing this for her

aaaaa has anyone gotten the blueprints yet;;;..