of these objects, we could elucidate the chemical evolution in and around this region; this topic is left for future study.

We acknowledge the anonymous referee for many useful comments to improve the manuscript. We express our thanks to Takahiro Naoi, Nagisa Oi, and Tatsuhito Yoshikawa who collected additional IRSF photometric data for our targets. We are also grateful to Subaru support astronomers, Miki Ishii, Yosuke Minowa, and Tae-Soo Pyo, for their help during our Subaru observations in 2010 and 2012. Martin Groenewegen provided the dataset for nearby template Cepheids which were published in 2013. A part of this paper was written in a hospital in Cape Town, South Africa, where the first author NM was treated after his accidental fall in the IRSF dome on May 3, 2014. NM is grateful to everyone, in both South Africa and Japan, who rescued and supported him after the accident; especially to Patricia Whitelock, John Menzies, Michael and Connie Feast, and Rie Matsunaga for their warm support. This work has been supported by Grants-in-Aid for Scientific Research (No. 22840008, 23684005, and 26287028) from the Japan Society for the Promotion of Science (JSPS).

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