A Phase III Confirmatory Study of K-237

Inclusion Criteria: Persons who meet all of the following criteria will be eligible for this clinical trial. 1. Males and females who are 12 years of age or older at the time of obtaining consent 2. Those who are confirmed positive for SARS-CoV-2 by antigen test or RT-PCR test using specimens (nasopharynx, nasal cavity, oropharynx, or saliva) collected within 120 hours prior to obtaining consent. 3. Patients who have fevers (37.5 degrees Celsius or higher) and/or at least one of the following symptoms of Score 2 or higher at a screening test: Myalgia, sore throat, diarrhea, nausea, vomiting, cough, and shortness of breath. 4. Patients with a room air oxygen saturation (SpO2) of 96% or higher at the time of the screening test. Exclusion Criteria: * Subjects who meet any one of the following criteria will be excluded from this study. 1. Patients who have had symptoms caused by COVID-19 for more than 6 days on the day of initiation of study drug administration (Day 1) with the day of onset of symptoms as Day 0. 2. Patients who need to receive concomitant therapy or administration of prohibited drugs during the study period 3. Patients who have taken or received drugs that have or may have antiviral activity against SARS-CoV-2 within 2 weeks prior to the start of study drug administration. 4. Patients currently using antiviral drugs 5. Patients with suspected complications of infectious diseases other than COVID-19 6. Subjects with a history of COVID-19 within 1 month prior to obtaining consent 7. Persons whose weight at the time of the screening test falls into the following categories (The first decimal place of the weight shall be rounded off.) 1) Those who are 18 years of age or older at the time of consent and weigh less than 25 kg or more than 127 kg 2) Those who are between 12 and 18 years of age and weigh less than 40 kg or 127 kg or more at the time of obtaining consent. 8. Patients undergoing dialysis treatment 9. Patients wno have severe liver dysfunction (hepatic dysfunction, hepatic fibrosis, etc.) 10. Patients with poorly controlled hypertension (systolic blood pressure (SBP) of 180 mmHg or higher or diastolic blood pressure (DBP) of 110 mmHg or higher) 11. Patients with complications of diabetic retinopathy, diabetic nephropathy, or diabetic neuropathy 12. Patients with heart failure of NYHA Class III or higher 13. Patients with malignant tumors or those judged to have a high possibility of recurrence 14. Patients requiring oxygen therapy 15. A person who has a complication of methemoglobinemia or any other disease that may cause measurement error of the pulse oximeter 16. Patients with a history of serious drug allergy (anaphylactic shock, etc.) 17. Pregnant women, lactating women, or women who plan to become pregnant or lactate during the study period 18. Subjects who have had more than 400 mL of whole blood drawn within 16 weeks or more than 200 mL within 4 weeks prior to obtaining consent, or component blood (plasma and platelet components) drawn within 2 weeks 19. Patients who have been administered IVM. 20. Those who have participated in other clinical trials and received medication at the time of obtaining consent, or those who have received an investigational drug other than placebo for less than 16 weeks 21. Others who are judged by the investigator or others to be inappropriate to participate in the study.