If you're willing to give up the blanks, here's a rarely known feature of Perl's globbing permutation functionality:

    for(<{ch}{i,}{ts}{a}{k}{u,}{s}{i,}#>) {
        print "$_\n";
    }
[download]

It prints:

    chitsakusi#
    chitsakus#
    chitsaksi#
    chitsaks#
    chtsakusi#
    chtsakus#
    chtsaksi#
    chtsaks#
[download]