Please see attached file for examples of the behaviour.
bar_chart_ok_japanese.pdf - Shows bar chart is showing the legend and X-axis in Japanese.
rader_chart_ok_english.pdf - Shows radar chart with English legend and graph points.
rader_chart_ok_html_japanese.jpg - Shows radar chart displaying correctly in HTML format
rader_chart_ng_japanese.pdf - Shows radar chart no displaying legend and graph point in Japanese.
radar_chart_sample.prpt - Sample report with Japenese data.
radar_chart_sample_english_data.prpt - Sample report with English data.
The problem appears to be caused by the font for the legend and graph point not being embedded, resulting in a non-Japanese enabled font being used in the PDF.
You'll see two sets of embedded fonts when the properties of the bar chart PDF file is examined.
You'll one set of embedded font and one default font when you examine the radar chart in Japanese.
The report properties appear to have the 'embed font' attribute set in the sample reports.