Part 1 : To evaluate the safety of single-dose KK3910 in healthy volunteers. Part 2 : To evaluate the safety of multiple-dose KK3910 in patients with essential hypertension. Part 3 : To assess the safety profile of repeated dosing of KK3910 in an additional hypertension cohort.

Inclusion Criteria: Part 1

• Voluntary consent to participate in this study must be given (in writing)
• Japanese healthy adults or non-Asian healthy men 18 to < 55 years at the time of informed consent ( Japanese healthy adults 65 to < 80 years for the elderly cohort)
• BMI is within the specified range at screening

Inclusion Criteria: Part 2

• Voluntary consent to participate in this study must be given (in writing)
• Japanese patients with essential hypertension, aged 18 to <65 years at the time of informed consent
• BMI is within the specified range at screening

Inclusion Criteria: Part 3

• Voluntary consent to participate in this study must be given (in writing)
• Japanese patients with essential hypertension, aged 18 to <80 years at the time of informed consent
• BMI is within the specified range at screening

Exclusion Criteria: Part 1

• History of any respiratory disease, heart disease, gastrointestinal disease, renal disease, liver disease, psychiatric disorder, autoimmune disease, or malignant tumor that may affect assessments in the study, as judged by principal investigator or subinvestigator.
• History of or current drug allergy
• History of or current alcoholism or drug addiction
• Smoking within the specified period
• infection within the specified period
• Any condition judged by the investigator or subinvestigator to be unsuitable for participation in the study

Exclusion Criteria: Part 2

• History of any respiratory disease, heart disease, gastrointestinal disease, renal disease, liver disease, psychiatric disorder, autoimmune disease, or malignant tumor that may affect assessments in the study, as judged by principal investigator or subinvestigator.
• History or of current drug allergy
• History of or current alcoholism or drug addiction
• Pregnant or breastfeeding patients, or patients willing to have a child during the study
• Smoking within the specified period
• infection within the specified period
• Any condition judged by the investigator or subinvestigator to be unsuitable for participation in the study

Exclusion Criteria: Part 3

• History of any respiratory disease, heart disease, gastrointestinal disease, renal disease, liver disease, psychiatric disorder, autoimmune disease, or malignant tumor that may affect assessments in the study, as judged by principal investigator or subinvestigator.
• History or of current drug allergy
• History of or current alcoholism or drug addiction
• Pregnant or breastfeeding patients, or patients willing to have a child during the study
• Smoking within the specified period
• infection within the specified period
• Any condition judged by the investigator or subinvestigator to be unsuitable for participation in the study

There is a plan to make IPD and related data dictionaries available. The datasets generated and/or analyzed during the study sponsored by Kyowa Kirin will be available in the Vivli repository, https://vivli.org/ourmember/kyowa-kirin/ as long as conditions of data disclosure specified in the policy section of the Vivli website are satisfied.