But in the chaos that followed, the friends' efforts to keep in touch via social media soon floundered.
An initial flurry of contact and relieved connection was followed by eerie silence.
Shimzu, 28, was especially alarmed that she could not reach her parents on the west coast of Japan.
"I was really worried," she said. "I just couldn't sleep that night."
It took two days to get through to them by phone. They were shaken, but unharmed.
For the first time in Shimzu and Kuki's lives, power failures and dead batteries half a world away had cut them off from the instantaneous communication they take for granted.
Shimzu's relatives in Sendai, the area hit hardest by the tsunami, were nowhere to be found.
"I didn't know what to think," said Shimzu, who is a UCLA alumna and working in web design.
After five days, news finally came -- by way of an old-fashioned pay phone and word-of-mouth.
"They got into the long line for the public telephone and called our other relatives," Shimzu said. "Those relatives called everyone else and we got the information that they were OK."
Kukio has not been as fortunate -- a cousin in Sendai is still missing.
"You hear about these amazing stories about how people have been recovered from the rubble, or are doing fine but just haven't been located," she said. "The hope is that everything is fine or that she may have escaped in time."
Without access to social networks -- or phones for that matter -- Sendai residents and their loved ones abroad have turned to a Japanese tradition of forbearance known as "gaman."
"It means keep your head up, keep going forward, hold it in, just power through," Kuki said.
It's a practice the women have come to rely on, with Facebook and Twitter falling short.
"Its frustrating when the only means through which you could possibly attain a sense of relief is by posting on someone's wall and waiting and waiting to get a response," Kuki said. "All you can do in that kind of situation is to wait, to pray, and hope for the best."
It's that kind of resolve that best describes "gaman." It's a national mentality perhaps rooted in Japan's Bushido, a Samurai code of ethics highlighting loyalty, honor and self sacrifice.
"I certainly had to rely on 'gaman' to keep my spirits up and not let myself be overcome with panic and overwhelmingly concern," Kuki said. "Part of 'gaman' is patience, and this was certainly key in handling the emotional anxiety."