connective N5 common politewritten
けれども — but / however / although
けれども
Builds on けれど
A full written guide for けれども is on the way.
This point is mapped in the grammar tree, but its examples, formation table and usage notes haven't been written yet. The fastest way to learn it now is to meet it in real sentences inside Jengo.
See けれども in real sentences
Jengo shows けれども the way you actually meet it: inside real Japanese sentences, so it sticks instead of staying an abstract rule.
Study it in JengoSources Compiled with reference to A Dictionary of Advanced Japanese Grammar, A Dictionary of Basic Japanese Grammar. Editorial confidence: medium.