I enjoyed the build up but the ending left me thinking "that's it?". If you were absolutely bent on having a sad ending I would of at least added a scene where you go to check on Reiko and you see the two struggling against one another. Have Seiichi die during the struggle if you really wanna give the middle finger to the player. The aftermath could be conveyed through a news report or something.
Up until the ending it was entertaining but the ending itself just felt so sudden.