Sacubitril/valsartan has demonstrated its prognostic advantageousness over enalapril in patients with heart failure with a reduced ejection fraction. However, the optimal therapeutic strategy using sacubitril/valsartan in real-world practice, particularly among a Japanee cohort, remains uncertain. A 75-year-old man with systolic heart failure and chronic kidney disease was administered sacubitril/valsartan. Plasma B-type natriuretic peptide transiently increased, accompanied by an increase in the urine volume, which allowed us to terminate loop diuretics. The estimated glomerular filtration rate as well as heart failure symptom improved at the one-month follow-up. Sacubitril/valsartan might be a promising option to preserve the renal function and improve clinical outcomes when the dose of concomitant diuretics can be decreased, although further large-scale studies are warranted to validate our hypothesis.