Galaxy stellar mass function at z = 0.25 in NEWHORIZON and the HSC-SSP survey. The light blue squares and dark blue circles with error bars indicate the NEWHORIZON stellar mass function for all galaxies (offset by 0.15 dex) and only uncontaminated galaxies (with a volume correction applied). The black line indicates the median galaxy stellar mass function from 100 random pointings from a volume of the HSC-SSP deep layer with the same volume as NEWHORIZON and the black error bar indicates the 90% scatter in the mass function at the low-mass end. A comparison is made with additional mass functions from literature (Sedgwick et al. 2019a; Davidzon et al. 2017; Tomczak et al. 2016; Song et al. 2016; Grazian et al. 2015; D’Souza et al. 2015; Fontana et al. 2014; Bernardi et al. 2013; Ilbert et al. 2013; Baldry et al. 2012; Bielby et al. 2012; González et al. 2011; Pozzetti et al. 2007), which are shown as thin coloured lines. The thick purple dotted line indicates the NEWHORIZON mass function constructed using the Sandage et al. (1979) method (STY) and including selection effects.