As the rural farming population decreases and ages, there is a gradual decrease in watermelon cultivation. Although the production of small- and medium-sized watermelons is increasing, typical large-sized watermelons are still, which culminates in their cultivation being a burdensome task for elderly farmers. To address this issue, we developed a watermelon variety, namely, ‘Soonzero,’ that does not require pruning, as its secondary lateral branches do not occur in primary lateral branches after the growing point it cut. ‘Soonzero’ is a diploid and broad, elliptical watermelon; its uniqueness lies in its green skin and pinkish-red flesh. The conspicuousness of veining on the skin is weak, and the width of the fruit's stripes is similar to that of ‘Sambokggul.’ In terms of variable characteristics, in this study, this variety produced 452 seeds, a yield similar to that of ‘Sambokggul,’ with the length and width of the resultant fruit being 25.5 and 24.2 cm, respectively. Additionally, the pericarp of ‘Soonzero’ had a thickness of 1.0 cm and a total soluble solid content of 11.8 °Bx. The yield of ‘Soonzero’ was found to be 6,150 kg per 10 acres, similar to that of ‘Sambokggul.’ However, ‘Soonzero’ differs from the control in terms of the following traits: fruit stripe width, flower spot shape, and the conspicuousness of veining on the fruit. In conclusion, the secondary lateral branchless varieties developed at the Watermelon Research Institute are expected to be quickly distributed to farmers with excellent quality by making up for their shortcomings by transferring technology to breeding companies and giving consumers the opportunity to choose according to their purchasing preferences. Above all, since it can reduce the labor required to remove lateral branches, it will help farmers grow watermelons more easily by solving aging and labor issues, which are chronic problems in rural areas (Grant number 8807).