How long until Miku Expo? How long until Magical Mirai? The answer to these questions will be at your fingertips with this toy app.
If you'd like a Flatpak, you can click this button:
Otherwise, to build it yourself you'll need gtkmm-4 and a C++23 compiler.
Fedora 40 instructions:
# sudo dnf install gtkmm4.0-devel meson gcc-c++ libadwaita-devel
# meson setup build
# ninja -C build
# # Install to e.g. /usr/local. Needed to install gsettings schema.
# sudo ninja -C build install
# build/src/mikuexpo-countdown # (This runs the program)
Other distros you can figure out yourself..!