For me it'd be my back to back first time clear of UFO normal with Sanae : I've had a handfull of 1cc at that point but was still a bit of a rookie, and I got BATTERED by the game as I had to try so many times for like 2 or 3 hours per day over the course of 2 weeks or so : had some nasty moments where I've failed at the absolute last part of the game, went from full life to only 2 remaining against Shou, and even an extra dumb one where I mechanically reseted a very good run into stage 4 cuz I paused in order to check something out ... eventually, I had commited my routes to muscle memory, disciplined myself not to chase after the stupid UFOs, even remembered which enemies dropped which non-changing UFOs, and bombed much more freely ... when I beat the game, it was with Sanae B and it was NOT EVEN CLOSE : had like 5 or 6 lives remaining, and I didn't feel anything in particular ... then I proceeded to check the extra stage, and a thought crossed my mind like "hmm, would the snakes be more comfortable against this opening section ?" so I checked Sanae A, she wasn't available so I quickly had another run with her, got a clear with 4 lives remaining, tried her a bit in the extra and was like "yeah, I like the frogs better", then it hit me : I did it ! I conquered the game ! Smacked my foot hard on the ground, stretched for a bit, and kept playing the extra stage for fun with a dumb grin on my face until 3 AM. Game's brutal, but man, seeing the effort pay of was extremely satisfying ...