As usual, I'm playing with RG Otchan every day.
This time, I tried to make a light saber light up realistically.
I searched the internet for information from previous builders, and this is what I found.
Lithium battery with LED! (in the style of Nobuyo Oyama)
It's called Mirait!  A mix of Bright and Mirai, a perfect name for a Gunpla.
The beam saber-like appearance seemed intentional on Hiromi Sangyo's part, but it seems to be a fishing item.
Too much light leaked out, so I covered it with plastic pipe about 3mm in diameter to give it the appearance of a beam saber, but it turned out poorly.

Can You Shine? (Part 1) | BALCAR's Gunpla works