\documentclass[border=15pt, multi, tikz]{standalone}
\usepackage{import}
\subimport{../../layers/}{init}
\usetikzlibrary{positioning}

\newcommand{\up}{0.25}
\newcommand{\down}{0.25}
\newcommand{\arrowlength}{4}

\begin{document}
\begin{tikzpicture}
\tikzstyle{connection}=[ultra thick,every node/.style={sloped,allow upside down},draw=\edgecolor,opacity=0.7]

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%% Draw previous connections
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\draw [connection]  (-\arrowlength,\up,0) 
node[anchor=south west,scale=2.1]{$p(x^{(t)})$}   
-- node {\midarrow} (0,\up,0);  
\draw [connection]  (0,-\down,0)  -- node {\midarrow} ++(-\arrowlength.0,0)
node[anchor=north west,inner sep = 10, xshift=-25,scale=2.3]
{
    $\frac{\partial L}{\partial E_\mathcal{S}}\frac{\partial E_\mathcal{S}}{\partial p}$
};
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%% Draw Layer Blocks
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\pic[shift={(0,0,0)}] at (0,0,0) {Box={name=crp1,caption=SoftmaxLoss: $E_\mathcal{S}$ ,%
        fill={rgb:blue,1.5;red,3.5;green,3.5;white,5},opacity=0.5,height=20,width=7,depth=20}};
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%% Draw next connections
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\draw [connection]  (crp1-east)++(0,\up,0) -- node {\midarrow} ++(\arrowlength.0,0) 
node [anchor=south east,scale=2.1]{$E_\mathcal{S} [p;\theta]$};

\draw [connection]  (crp1-east)++(\arrowlength,-\down,0)  
node[anchor=north east,inner sep = 10, xshift=25,scale=2.3]
{
    $\frac{\partial L}{\partial E_\mathcal{S}} = \lambda_\mathcal{S}$
}   
-- node {\midarrow} ++(-\arrowlength,0,0);
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

   		

\end{tikzpicture}
\end{document}