The main purpose of this study is to see if LY3985297, the study drug, is safe and well-tolerated when given as a single dose or as multiple doses either through an intravenous (into a vein) or a subcutaneous (under the skin) injection in healthy participants. Study will also evaluate how much of the study drug LY3985297 gets into the blood stream and how long it takes the body to remove it.

The study is conducted in two parts (part A and B), each part has a separate treatment cohort.

The study will last up to approximately 116 days for part A, and 145 days for part B, including the screening period.

Inclusion Criteria:

• Participants must be overtly healthy, as determined by medical evaluation.
• Have a body mass index of 18.0 to 32.0 kilograms per square meter (kg/m²), inclusive, and a minimum body weight of 45.0 kg.
• Participants must be assigned male or female at birth and not of childbearing potential.
• Have normal blood pressure, pulse rate, electrocardiogram (ECG), clinical laboratory test results that are acceptable for the study.
• Have venous access sufficient to allow for blood sampling.

For Part A Cohorts 5, 6, and 7:

• Participants must be first-generation Japanese only, defined as the participant's biological parents, and all of the participant's biological grandparents must be of exclusive Japanese descent and born in Japan. Or
• Participants must be first-generation Chinese only, defined as the participant's biological parents, and all of the participant's biological grandparents must be of exclusive Chinese descent and born in China.

Exclusion Criteria:

• Have a current or recent acute, active infection. For at least 30 days before screening and up to the randomization visit (Day 1).
• Had any surgical procedure (except for minor surgery requiring local or no anesthesia and without any complications or sequelae) within 12 weeks prior to screening or intend to during the study.
• Have a history of multiple or severe allergies, or an anaphylactic reaction, to prescription or nonprescription drugs or food.
• Show evidence of active or latent tuberculosis (TB).
• Have one of the following infections: hepatitis B, C virus or human immunodeficiency virus (HIV).