A Study of TAK-755 in Adults With Acute Ischemic Stroke

Acute ischemic stroke (AIS) is a medical emergency that happens because of a sudden stop of blood flow to a part of the brain. This happens when a blood clot forms within the vessel (known as thrombotic occlusion) or a clot originating from somewhere else blocks a blood vessel (known as embolic occlusion). Strokes can cause serious health problems, death, and affect one's quality of life. To reduce long-term damage, it is important to restore blood flow to the brain as soon as possible. The main aim of this study is to check how safe TAK-755 is, and how well adults with AIS tolerate it. Other aims are to check how well TAK-755 helps participants to manage their everyday activities and to understand whether it helps reduce the seriousness of their stroke symptoms when compared to placebo. A placebo looks like TAK-755, but does not have any medicine in it, to make sure participants do not know which treatment they are taking. The participants will receive TAK-755 or placebo once; afterwards, their health will be monitored for about 3 months (90 days). All participants, regardless of their assignment to either TAK-755 or placebo, will receive the usual treatment for AIS as per the hospital's normal practice.

Inclusion Criteria: Informed Consent: 1. The participant or legally authorized representative has provided informed consent or deferred consent eligibility confirmed before the initiation of any trial procedures. Age: 2. greater than and equal to (\>=) 18 years of age, inclusive, at the time of signing the Informed Consent Form (ICF) or confirmation of deferred consent eligibility. Clinical Characteristics: 3. Clinical diagnosis of AIS. 4. Onset of stroke symptoms within 24 hours of randomization. Wake-up strokes may be included if Last Known Well is within 24 hours of randomization; time of onset will be considered the time of Last Known Well. 5. National Institutes of Health Stroke Scale score of 5 to 25, indicating moderate to severe stroke. Participants with an NIHSS score of 5 are eligible only if at least 1 predefined disabling neurological deficit is present, as defined by one or more of the following NIHSS criteria: * Complete hemianopia (NIHSS visual score \>=2). * Aphasia impairing meaningful communication (NIHSS language score \>=2). * Motor deficit with inability to sustain effort against gravity (NIHSS left or right motor arm or leg score \>=2). 6. Estimated Modified Rankin Scale score less than (\130 kilograms (kg) or \