This clinical trial is to provide a minimally invasive treatment option in which the targeted prostate cancer tissue is killed by cryoablation at extremely low temperatures only in the specific area of cancer "that should be treated for saving of life"; while, leaving a portion of the normal prostate tissue that is not cancerous. It is a treatment, named by "focal therapy" for "clinically localized prostate cancer". As this new treatment is aiming to treat only specific prostatic area of cancer, it is different from the invasive conventional treatment to remove the entire prostate gland. The goal is to achieve both to control of known cancer by treating only the cancerous area and to maintain of QOL (Quality-of-life) by leaving of the other normal prostate tissue and its surrounding organs intact resulting in prevention of urinary-leakage and sexual-dysfunction as the complications.

This trial will to provide an ultrasound-guided targeted cryoablation of known cancer lesions in patients diagnosed with clinically localized prostate cancer, and this trial will assess effectiveness for up to post-operative 6 months and safety for up to postoperative 12 months. This trial will assess patient quality of life (QOL) as well.

Inclusion Criteria:

1. Patients who have a PI-RADS category 3 or 4 lesion on MRI image at enrollment and who have a single lesion with a Gleason score 7 or 8 on histopathology of the prostate needle biopsy at enrollment; or, patients who have a PI-RADS category 4 or 5 lesion on MRI image at enrollment and who have a single lesion with a Gleason score 6 or 7 on histopathology of the prostate needle biopsy at enrollment
2. Patients with prostate cancer that is clinical stage T2c or lower (T1a-T2cN0M0) according to the TNM Classification as determined during enrollment
3. Patients between the ages of 20 and 85 when providing consent to participate in this trial
4. Patients from whom consent is obtained prior to enrollment in this trial

Exclusion Criteria:

1. Patients to have a lesion identified as PI-RADS category 4 or 5 on MRI images at enrollment and who have a single lesion with a diameter of less than 10 mm and Gleason score of 6 on the histopathology of the prostate needle biopsy at enrollment (the lesion is referred to as "non-target lesions") (the diameter of the lesion is defined as the longer one of the lesion diameter identified on MRI images at enrollment or the tumor length as measured on histopathology of prostate needle biopsy)
2. Patients to have 4 or more non-target lesions (non-target lesions are defined as the lesions defined in exclusion criterion 1, or lesions with PI-RADS category 3 on MRI image at enrollment and Gleason score 6 on biopsy at enrollment)
3. Patients to have a lesion with PI-RADS category 5 on MRI image at enrollment and Gleason score 8 on histopathology of prostate needle biopsy at enrollment (the lesion is referred "excluded lesions")
4. Patients with a serum prostate-specific antigen (PSA) level over 20 ng/ml during enrollment
5. Patients in whom the distance from the target prostate cancer lesion to an external urinary sphincter is 5 mm or less on MRI images (coronal or sagittal) obtained during enrollment
6. Patients who have undergone surgery, drug therapy, or radiation therapy for prostate cancer prior to enrollment
7. Patients who have received an antiandrogen for benign prostatic hyperplasia prior to enrollment
8. Patients using absorbent pads or adult diapers due to urge incontinence
9. Patients with active multiple cancers
10. Patients for whom MRI scans are contraindicated
11. Patients in whom transrectal ultrasound cannot be performed for some reason, such as a constricted rectum
12. Patients with a prothrombin time<50% or platelet count<60,000/mm3 during enrollment
13. Patients deemed to be ineligible by an investigator

Because the prostate is an organ that only men have.