unset key
set yrange [0:8]
set term pngcairo enh font "Times, 10" size 480,360
set out "plot_histograms.png"
set label "plot with histograms" at sc 0.4, 0.85 font "Helvetica,18"
set ylabel "Ｙ軸 IPA明朝" font "IPAMincho,12"
set style fill solid 0.75
plot for [COL=2:5] 'histo.dat'  u COL:xtic(1) w histograms