Indent unnumbered chapter in TOC with multitoc (in presence of tocstyle)

Question

I'm having a problem mixing multitoc with tocstyle. What I want is my unnumbered chapters in the TOC to be indented (in this case \addchap{Introduction}).

I figured out that \usepackage[toctextentriesindented]{tocstyle} will give me the indentation that I want, but it changes the font and formatting. The best solution will be to get the desired indentation without using tocstyle, i.e., achieve my desired indentation only within the confines of \usepackage[toc]{multitoc}.

MWE:

%XeLaTeX
\documentclass[11pt]{scrbook}

\usepackage[toc]{multitoc}
    \setlength{\columnseprule}{0.5pt}

%\usepackage[toctextentriesindented]{tocstyle} % this works but changes the formatting

\begin{document}

\tableofcontents

\addchap{Introduction}
\chapter{Chapter A}
\chapter{Chapter B}

\end{document}

Desired indentation of "Introduction" but not the font/formatting that I want:

Desired font/formatting but without the indentation of "Introduction" that I desire:

Answer 1

Update

Note that it is not recommended to use package multitoc. It is outdated and seems to be not maintained anymore. Markus Kohm has warned me that the usage of multitoc results in empty other lists (LOF, LOT and new defined lists).

Here is a suggestion that directly uses the multicol package for the TOC with two columns:

\documentclass[11pt,toc=indentunnumbered]{scrbook}

\usepackage{multicol}
\BeforeStartingTOC[toc]{\begin{multicols}{2}}
\AfterStartingTOC[toc]{\end{multicols}}
\setlength{\columnseprule}{.5pt}

\begin{document}
\tableofcontents
\addchap{Introduction}
\chapter{Chapter A}
\chapter{Chapter B}
\end{document}

Result:

---

Original answer

Use KOMA-option toc=indentunnumbered:

\documentclass[11pt,toc=indentunnumbered]{scrbook}

\usepackage[toc]{multitoc}
    \setlength{\columnseprule}{0.5pt}

\begin{document}
\tableofcontents
\addchap{Introduction}
\chapter{Chapter A}
\chapter{Chapter B}
\end{document}

Result: