The Furigana plugin for Obsidian adds functionality for marking selected text with ruby annotations, allowing users to display furigana readings for kanji. This is particularly useful for learners of Japanese, as it provides immediate access to pronunciation guides directly within Obsidian. The plugin enables users to highlight text and apply the `<ruby>` HTML tag to show furigana readings. Currently, the plugin is focused on this annotation feature, with plans to add automatic kanji-to-hiragana conversion in future updates.