Complex sentence: When WWII broke out, Jun, along with his wife Tomoe, would join the Office of Strategic Services, adopting the pseudonym Mitsu Yashima, and Jun adopting the pseudonym Taro Yashima to protect there son who was still in Japan.
Split into simpler sentences: When WWII broke out, Jun, along with his wife Tomoe, would join the Office of Strategic Services. She adopted the pseudonym Mitsu Yashima, and Jun the pseudonym Taro Yashima, to protect their son who was still in Japan.