"I am deeply hurt by the grievous situation in the affected areas. The number of deceased and missing increases by the day. We cannot know how many victims there will be. My hope is that as many people possible are found safe," Akihito, 77, said.
He added: "I hope from the bottom of my heart that the people will, hand in hand, treat each other with compassion and overcome these difficult times." He also urged survivors not to "abandon hope."
The nuclear crisis, which Akihito said "deeply worried" him, appeared to worsen Wednesday, as a second reactor unit at the Fukushima Daiichi plant may have ruptured – prompting new fears that a wide release of radioactive material was possible.
Kim Kyung-Hoon / Reuters / Landov
Meanwhile, the rest of the world has been mobilizing to help Japan in its hour of need. Here are some ways you can get involved and help:
The Portland, Ore.-based Mercy Corps is accepting donations to help survivors of Japan's earthquake and tsunami through their longstanding partner, Peace Winds Japan. Donations will go to meeting the immediate and longer-term needs of the survivors. You can text MERCY to 25283 to donate $10.
Convoy of Hope's Disaster Response team is in contact with partners in Japan and identifying areas in the greatest need of assistance. You can donate online at convoyofhope.org or text TSUNAMI to 50555 to donate $10 toward the relief efforts.
AmeriCares is asking for donations so they can provide medicine and medical supplies to victims of the disaster.
Global Giving has set up a relief fund where you can make a donation, which will be distributed to relief and emergency services in the affected region.
Direct Relief International is reaching out to medical teams and emergency responders to offer assistance.
Save the Children is mobilizing a response to the disaster in Japan with a focus on helping the youngest victims.
International Medical Corps is sending medical supplies and relief teams to Japan. Help by donating $10 by texting MED to 80888.
Make a $10 donation to the Red Cross by text messaging REDCROSS to 90999 or visit redcross.org to donate online.
If you're looking for a loved one in the disaster area, Google People Finder is a good place to start.