In the US there is a requirement for car manufacturers to make all manuals freely available. These links are for the US models which can be different to the Japanese or UK imports but still very useful information.
Nissan USA Owners Portal - select Leaf as the car then the year to see owners manuals
Full set of manuals including service manuals - note different model year option on right of page.
Japanese manuals need translating but can be more accurate for your model:
Nissan Japan manuals - select the year for your model from this page
Note you need your browser to automatically translate the page to navigate to the desired manual.