Ghibli Park is built on top of the former site of the 2005 expo, so it contains a lot of woods, streams etc unrelated to Ghibli. I think this is a drainage ditch but I thought it was pretty.
https://files.mastodon.social/media_attachments/files/113/422/526/935/348/310/original/7e1b5edca8807a4f.jpg