[ST09-007] - Shinobu (Starter Deck 9: Yamato)

I attacked with this Character when both me and my opponent had 1 Life card left, and my opponent blocked my attack with "ST09-007 Shinobu". At this time, if my opponent activates the [On Block] effect of "ST09-007 Shinobu" and their Life cards are reduced to 0, will I win the game based on this Character's effect?

No, you will not win the game.