Cursor shape won't change in vim and neovim

[ghost]

when going to insert mode in vim or neovim cursor shape won't get changed to a vertical bar. it works fine in xterm. so i think it's not a vim problem but rather a mlterm problem?

[arakiken]

In my environment, mlterm 3.9.2 changes the cursor shape of vim or neovim to a vertical bar by configuring ~/.vimrc as follows.
let &t_SI .= "\e[5 q"
let &t_SR .= "\e[3 q"
let &t_EI .= "\e[1 q"

How do you configure vim or neovim to change the cursor shape ?
(I'm not so much familiar to vim or neovim, sorry.)