* Mood relies on dollar-yen levels - traders
* Nikkei down 1.1 pct for week, set to post 4th weekly losses
* Mitsubishi Heavy stumbles after unit says will delay delivery of first regional jet
By Ayai Tomisawa
TOKYO, Dec 25 (Reuters) - Japan's Nikkei share average was flat on Friday morning in holiday-thinned Christmas trading, with the slightly stronger yen capping risk appetite.
The Nikkei was flat at 18,783.05 in midmorning trade after moving in and out of the black. Although markets are open in Japan, trading was limited with many other financial markets closed for the Christmas holiday.
For the week, the Nikkei has fallen 1.1 percent and was poised for a fourth weekly losses.
"The mood pretty much relies on the dollar-yen levels today," said Yutaka Miura, a senior technical analyst at Mizuho Securities. "Today's activity will most likely be futures-led trading and since volume is expected to be thin, the market can get volatile."
Exporters lost ground, with Toyota Motor Corp and Honda Motor Co each falling 0.5 percent and Panasonic Corp dropping 0.6 percent.
The dollar hit a near two-month low against the yen overnight. It was last at 120.22 yen.
Financials also lost ground, with Mitsubishi UFJ Financial Group and Sumitomo Mitsui Financial Group each shedding 1.3 percent.
Mitsubishi Heavy Industries tumbled 3.8 percent after its aircraft unit Mitsubishi Aircraft Corp said on Thursday it would delay the first delivery of its regional jet by around one year from the original plan.
The broader Topix was flat at 1,523.52 and the JPX-Nikkei Index 400 rose 0.1 percent to 13,757.31. (Editing by Shri Navaratnam)