A Clinical Trial of NS-863 in Participants With Pulmonary Hypertension Associated With Interstitial Lung Disease (PH-ILD)

Inclusion Criteria: Participants must meet all of the following criteria to be included in the trial: * Ability to provide written informed consent prior to participation in the trial, which includes the ability to comply with the requirements and restrictions listed in the informed consent form (ICF). Participants must be able to read, comprehend, and write at a level sufficient to complete trial-related materials * Adult male or female participants 18 (19 years in South Korea) to 80 years of age at the time the ICF is signed * A confirmed diagnosis of the following WHO Group 3 PH based on HRCT imaging, which demonstrates the following evidence of ILD performed within 6 months prior to starting the Treatment Period: 1. ILD 2. CPFE: only allowed for participants with 15% or less emphysema, and the extent of the ILD must be greater than that of the emphysema. Participants may have any form of ILD (including IIP, IPF, and connective tissue disease) or CPFE * Results of the RHC within 35 days prior to Day 1 and meet all of the following criteria: 1. Participants receiving treatment with endothelin receptor antagonists, phosphodiesterase type 5 inhibitors, soluble guanylate cyclase stimulators, prostacyclin analogs or prostacyclin receptor agonists, and/or calcium channel blockers are eligible only if on a stable dose for at least 90 days prior to RHC at baseline and throughout the Screening Period. For infusion prostacyclin analogs, dose adjustment based on the participant's body weight is allowed per medical practice. 2. Participants on chronic medication for underlying lung disease (ie, pirfenidone, etc.) are eligible only if on a stable dose for at least 90 days prior to RHC at baseline and throughout the Screening Period 3. Participants receiving treatment with oxygen therapy are eligible only if beginning for at least 30 days prior to RHC at baseline and throughout the Screening Period, and on a stable dose of oxygen for 30 minutes before RHC * Valid 6MWD * Baseline FVC \<70% (only for participants with connective tissue disease). * Women of childbearing potential (WOCBP) must have a negative pregnancy test before receiving the trial treatment and must agree to use contraception from the Screening Visit to at least 30 days after the last dose of the trial treatment. Male participants who could potentially cause pregnancy must agree to use contraception from the Screening Visit to at least 90 days after the last dose of the trial treatment to avoid pregnancy in their partners * Able to complete the scheduled visits and follow the instructions of the investigator Exclusion Criteria: Participants meeting any of the following criteria at the Screening Visit or baseline are ineligible to participate in this trial: * Have a diagnosis of PAH or PH for reasons other than WHO Group 3 PH-ILD as outlined in inclusion criterion 3 * Have evidence of clinically significant left-sided heart disease, as defined by: a. LVEF \<40% Notes: Participants with abnormal LV function attributable entirely to impaired LV filling due to the effects of RV overload (ie, RV hypertrophy and/or dilatation) will not be excluded * Receiving \> 6 L/min of oxygen supplementation by any mode of delivery at rest at baseline * Moderate or severe liver, renal, blood, or psychiatric disease: 1. Moderate and severe hepatic impairment by the Child-Pugh scoring system (Class B and Class C) 2. Moderate and severe renal impairment by estimated glomerular filtration rate (eGFR) \<60 mL/min/1.73m2 3. Have mental disorders or other conditions that make it difficult to follow the protocol * History of clinically significant (per investigator's judgment) drug or alcohol abuse disorder within the last 6 months * Have mental disorders or other conditions that make it difficult to follow the protocol * History of calculus urinary * History of acute kidney injury within 12 weeks prior to the start of the Screening Visit * Participants who have hematuria (\>5 RBC/hpf) or proteinuria (urine albumin creatinine ratio \[UACR\] \>150 mg/g or urine protein creatinine ratio \[UPCR\] \>400 mg/g) at the Screening Visit * Have a deterioration of underlying disease or a lung or upper respiratory tract infection within 30 days prior to baseline * Initiation of pulmonary or cardiac rehabilitation within 12 weeks prior to baseline * At the time of consent, more than 1 year has passed since registration for lung transplantation, or surgery related to PH treatment is scheduled * Have diseases or symptoms that limit evaluation of 6MWT (eg, peripheral vascular disease, musculoskeletal disorders, and obesity) * Participants who have participated in another clinical trial involving a drug or medical device, or have received treatment with an investigational product (including investigational formulations of marketed products), within 30 days prior to the Screening Visit or within 5 terminal phase half-lives of the investigational product, whichever is longer * Life expectancy is less than 6 months * Acute pulmonary embolism within 90 days prior to baseline * Current cigarette or e-cigarette smokers or those who have quit within the past 6 months, with a history of ≥20 pack-years smoking * Participants who are pregnant, breastfeeding, or planning to become pregnant during the time of trial participation * Use of dual platelet inhibitor therapy * Severe acute or chronic medical or laboratory abnormality that may increase the risk associated with trial participation or trial treatment administration * Have a history of allergies to the excipients in the trial treatment * Known human immunodeficiency virus (HIV) positive status * Active hepatitis due to hepatitis B virus or hepatitis C virus * Use of any protocol prohibited medications. * Receipt of any live vaccine within 4 weeks prior to the first dose of trial treatment or expected need for live vaccination during trial participation, including at least 4 weeks after the last dose of trial treatment * The investigator has judged the participant as unwilling or unable to * comply with the protocol * Other concurrent disease and/or medical condition that, in the judgment of the investigator, may put the participant at risk or may influence the results of the trial or the participant's ability to complete the entire duration of the trial