documentclass{article}
usepackage{tikz}
usetikzlibrary{matrix,positioning,chains,scopes}

begin{document}
begin{tikzpicture}
    [
        myright/.style={
            draw},
        myleft/.style={
            myright,
            on chain,
            fill=cyan!30}
    ]
    % LEFT
    {[start chain=L going below,
      every node/.append style=myleft]
        node {X};
        node {Y};
        node {Z};
    }

    % RIGHT
    {[start chain=R going below]
        node [myright,right=of L-1] {belong to X};

        matrix [right=of L-2]
        {
            node [myright] {belong to Y};\
            node [myright] {also belong to Y};\
        };

        node [myright,right=of L-3] {belong to Z};
    }
end{tikzpicture}
end{document}

documentclass[tikz,border=10pt]{standalone}
usetikzlibrary{matrix,positioning,chains,scopes}
begin{document}
begin{tikzpicture}
  [
    myleft/.style={
      draw,
      fill=cyan!30}
  ]
  % LEFT
  {[start chain=L going below,
    every on chain/.append style={myleft},
    every node/.append style={on chain},
    ]
    node {X};
    {[start branch=X going right,
      every on chain/.append style={fill=none}
      ]
      node {belong to X};
    }
    node {Y};
    node {Z};
  }
  matrix (m) [row sep=2.5pt, matrix of nodes, every node/.append style={draw}] at (L-2 -| L/X-2)
  {
    belong to Y\
    also belong to Y\
  };
  node (z2) [draw] at (L-3 -| L/X-2) {belong to Z};
  % RIGHT
  {[start chain=R going below]
    chainin (L/X-2);
    chainin (m-1-1) [join];
    chainin (m-2-1) [join];
    chainin (z2) [join];
  }
end{tikzpicture}
end{document}

documentclass{article}
usepackage{tikz}
usetikzlibrary{calc,positioning,chains,scopes}

    begin{document}
begin{tikzpicture}[
  node distance = 10mm and 30mm,
    on grid,
    start chain = A going below,
    start chain = B going below,
 myright/.style = {draw, minimum height=4ex, minimum width=33mm,
                   on chain=A},
  myleft/.style = {draw, fill=cyan!30, minimum height=4ex,
                   on chain=B}
    ]
% LEFT
    begin{scope}[every node/.style={myleft}]
node {X}; % name=B-1
node {Y};
node {Z};
    end{scope}
% RIGHT
    begin{scope}[every node/.style={myright}]
node [right=of B-1]    {belong to X}; % name=A-1
node {belong to Y};
node {also belong to /};
node {belong to no one};
    end{scope}
end{tikzpicture}
    end{document}

documentclass{article}
    usepackage{tikz}
    usetikzlibrary{arrows.meta,chains,positioning,scopes}

    usepackage[active,tightpage]{preview}
    PreviewEnvironment{tikzpicture}
    setlengthPreviewBorder{3mm}

makeatletter
%---------------------------------------------------------------%
tikzset{
suspend join/.code={deftikz@after@path{}},
    node distance = 13mm and 44mm,
          on grid = true,
      start chain = A going below,
      start chain = B going below,
        MR/.style = {% My Right
            draw, minimum height=4ex, text width=31mm,
            inner sep=1mm, align=center, % left?
            on chain=A},
        ML/.style = {% My Left
            draw=cyan!60!black, rounded corners, fill=cyan!30,
            minimum width=4ex, inner sep=1mm,
            node contents={rotatebox{90}{#1}},
            on chain=B},
       arrow/.style = {thick,-{Triangle[]}},
       }
%---------------------------------------------------------------%
makeatother

    begin{document}
%---------------------------------------------------------------%
    begin{tikzpicture}
% LEFT BRANCH
node [ML=X]; % name=B-1
node [ML=Y];
node [ML=Z];
node [ML=WWW];
node [ML=QQ];
% RIGHT BRANCH
    begin{scope}[every node/.style={MR,join=by arrow}]
node [draw=none,
       right=of B-1]    {}; % name=A-1, auxiliary node which serves
                            % as placeholder for real left and right node
                            % (A-L) and (A-R) defined latter in
                            % the TOP part of this code
node [suspend join]    {belong to Y};
node                   {belong to Z};
node                   {belong to WWW, however text in this node has three lines};
node                   {belong to QQ};
    end{scope}
% TOP ROW LEAVES (horizontally are not on grid)
    begin{scope}[node distance=2mm,
                  every node/.style={MR}]
node (A-L) [ left = of A-1.center] {left top leave};
node (A-R) [right = of A-1.center] {right top leave};
    end{scope}
% RIGHT LEAVES
node (C-1) [MR, right = of A-3] {upper right leave};
node (C-2) [MR, right = of A-4] {lower right leave};
% ARROWS NOT DETERMINED BY "JOIN" MACRO
path[arrow]    (A-L) edge (A-2)    (A-R) edge (A-2)
                (A-3) edge (C-1)    (A-4)edge (C-2);
    end{tikzpicture}
%---------------------------------------------------------------%
    end{document}

documentclass{article}
    usepackage{tikz}
    usetikzlibrary{arrows.meta,calc,chains,fit,positioning,scopes}

    usepackage[active,tightpage]{preview}
    PreviewEnvironment{tikzpicture}
    setlengthPreviewBorder{3mm}

makeatletter
%---------------------------------------------------------------%
tikzset{
suspend join/.code={deftikz@after@path{}},
    node distance = 13mm and 44mm,
          on grid = true,
      start chain = A going below,
      start chain = B going below,
        MR/.style = {% My Right node
            draw, minimum height=4ex, text width=31mm,
            inner sep=1mm, align=center, % left?
            on chain=A},
        ML/.style = {% My Left node
            draw=cyan!60!black, rounded corners, fill=cyan!30,
            minimum width=4ex, inner sep=1mm,
            node contents={rotatebox{90}{#1}},
            on chain=B},
        FL/.style = {%Fake Left node
            node contents={rotatebox{90}{phantom{X}}},
            on chain=B},
        RL/.style = {%Fake Left node
             draw=cyan!60!black, rounded corners, fill=cyan!30,
             minimum width=4ex, inner xsep=0pt,
             label=center:rotatebox{90}{#1},
             node contents={}},
       arrow/.style = {thick,-{Triangle[]}},
       }
%---------------------------------------------------------------%
makeatother

    begin{document}
%---------------------------------------------------------------%

    begin{tikzpicture}
% LEFT BRANCH
node [ML=X];   % name=B-1
node [FL];     % auxiliary node which maintain branch on grid
                % real nodes will take a place latter
node [FL];
node [ML=WWWW];
node [ML=QQ];
% RIGHT BRANCH
    begin{scope}[every node/.style={MR,join=by arrow}]
node [suspend join,
       right=of B-1]    {belong to X}; % name=A-1,
node                   {belong to Y};
node                   {also belong to Y};
node                   {belong to WWWW, however text in this node has three lines};
node                   {belong to QQ};
    end{scope}
% REAL BLUE NODE, instead of FL
path   let p1 = (B-2 |- A-2.north),
            p2 = (B-2 |- A-3.south),
            n1 = {veclen(y2-y1,x2-x1)} in
        node[RL=Y,
             minimum height=n1,
             fit=(B-2) (B-3)];
% RIGHT LEAVES
node (C-1) [MR, right = of A-3] {upper right leave};
node (C-2) [MR, right = of A-4] {lower right leave};
% ARROWS NOT DETERMINED BY "JOIN" MACRO
path[arrow]    (A-3) edge (C-1)    (A-4)edge (C-2);
    end{tikzpicture}