10 minutes away from Hario, this is a must see for the family. Cherry Blossoms are in bloom end of March beginning of April. Free.
This park is one of my favorite places to take my family in Sasebo. It is free, and has a several play areas for the kids. This park features a free fall slide, and what we call "ultimate beast master", and has a "snowless" sledding hill. Snow slides cost 500 yen, and the hill can be used year round. Even though you rent a snow slide, snow isn't needed to slide down the hill (see picture of green hill in the pictures). There is also small zip line at the top.
Overall, this is the most fun a family can have in Sasebo...so much to do, and everything (aside from the slide rental) is free.
Cherry Blossoms in bloom until right around mid-April.
To get there, type in "Hario Village" or your originating point.