Arguably their greatest shining moment came around the time Izumi was born, in a conflict that came known as the Alphan Wars. The Alphan Wars were named after SD3's sister-colony on Alpha Draconis V, who were invaded by the politico-mercantile conglomerate known as the Draconis Combine. Together the Alphan Marines and the DAC - notably the 48th "Black Dragon" Lance, commanded by one Lt. Col. Mishima Akira - handed the Combine a brutal defeat and sent them packing out of the area.

Twenty-odd years later the Combine returned, bent on vindicating themselves after the humiliation of the Alphan Wars by crushing the Wolfpack and conquering Sigma-3. Due to an unexpected economic collapse from which they were still recovering, the Alphan Marine were unable to send any substantive force to aid the DAC; between that and a Combine army restructured around a fearsome new breed of BattleMechs, the battle went south with alarming speed. Eventually they called Izumi's father, the now-retired Colonel Mishima Akira, out of retirement in the hopes that he might be able to stem the tide; her mother Izari, possibly the most famous neurosurgeon in the sector, decided to go with him and lend what aid she could. Unfortunately, their efforts were in vain; the DC overran the colony and the elder Mishimas were killed in battle.

Izumi had joined the Corps a few years earlier as a medic, in a mostly-successful attempt to follow in both parents' footprints at once; but before the fight against the Combine really heated up, she got into a row with her CO and left in a huff. Her official records say "Honourable Discharge"; hot-tempered as she may have been, the CO realized shortly after the incedent that it was mostly her fault.