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Tropical cyclones and meiyu-baiu fronts, as the two main synoptic systems over East Asia, bring heavy rain during summers, but their long-term and vertical raindrop size distribution (RSD) features over the midlatitude Japan Islands are limited. Radar-based quantitative precipitation estimation (QPE) techniques require RSD observations. In this study, five-year observations from Tokyo with a ground-based impact Joss-Waldvogel disdrometer (JWD) and a vertically pointing micro rain radar (MRR) with a vertical range of 0.2&#8722;6.0 km were used to study the vertical structures of RSD and QPE parameters. The results showed that the convective rain associated with tropical cyclones had a maritime nature, while the rain associated with the meiyu-baiu front had a continental nature. The rain associated with tropical cyclones had a relatively higher concentration of raindrops and a larger average raindrop diameter than the rain associated with the meiyu-baiu front. The <i>Z</i>&#8722;<i>R</i> (radar reflectivity-rain rate) relationships (<i>Z</i> = <i>AR^b</i>) based on the JWD data for tropical cyclones, the meiyu-baiu front and total summer rainfall in Tokyo were <i>Z</i> = 189 <i>R</i>^1.38, <i>Z</i> = 214 <i>R</i>^1.35 and <i>Z</i> = 212 <i>R</i>^1.33, respectively. When the <i>Z</i>&#8722;<i>R</i> relationships obtained in this study were used to replace the operational relationship of <i>Z</i> = 300 <i>R</i>^1.4, the standard deviation of the rain rate was reduced from 5.50 mm/h (2.34 mm/h) to 2.34 mm/h (1.32 mm/h) for typhoon (meiyu-baiu front) rainfall, although the change for total summer rainfall was small. In addition, with increasing height below 4 km, the value of <i>A</i> and <i>b</i> decreased.