Hi!
Yes, some mates said Sansui at Shibuya, they are correct.
Sansui branches are located at Shibuya, Shinjuku, Ueno, and Ikebukuro.
I think Sansui Shibuya branch has larger SW tacke shop space than the other branches.
If you go to Shibuya, you can visit other fishing shops, Joshu-ya and Tackle Berry.
If you want to visit Mogi-san's shop, it takes around 40min by train from Shibuya station. You get on Tokyu Den-en-toshi Line at Shibuya or other stations and get off Azamino station.
Cheers!
TANIY from Tokyo