TL;DR
We propose to open HRMP communication between Shiden Network and Sakura Network. This will require actions on both chains.

Summary
We propose to open a bi-directional channel between Shiden Network and Sakura Network. The primary use cases will be:

1. To prepare for opening HRMP channel between Astar Network and Clover Network on Polkadot so that the $80M FDV worth of $CLV tokens can be transferred to Astar to be used in the ecosystem of Astar Network and the protocols built on top of the network.
2. $SKU can be transferred to Shiden to be used in the ecosystem of Shiden Network and the protocols built on top of the network.

Proposal
There is no on-chain proposal. The proposal created in this forum acts as an official proposal between Sakura Network and Shiden Network.

Technical details (WIP)
The procedure for opening the channels is as follows:

1. Sakura Network initializes a proposal to open Sakura Network to the Shiden Network HRMP channel via the Astar forum.
2. Wait until the proposal on step 1 gets approved & enacted.
3. Onboard your testnet on the Rococo relay chain and exchange public endpoints and parachain-ids.
4. Wait until onboarding was successful on testnet.
5. Shiden Network proposes to accept the Sakura Network to Shiden Network HRMP channel and open a Shiden Network to Sakura Network HRMP channel via [Astar MuliSig Governance Batch call].
6. Wait until the proposal on step 5 gets approved & enacted.
7. Sakura Network accepts the Shiden Network to Sakura Network HRMP channel.
8. Wait for another session on Kusama/or/Polkadot for the change to be effective.

These extrinsics need to be called with the parachain’s sovereign account as the origin. To achieve this, on the Sakura Network side we will use polkadot-xcm pallet to send XCM message to the relay chain, by executing the following extrinsic from the parachain. Shiden Network should make an open request call and an accept request call with its pallet.

As a prerequisite, the parachain’s sovereign account must contain at least 10 KSM to be locked as collateral (5 for each channel direction), plus some KSM to pay for XCM execution fees.

Discussion
https://forum.astar.network/t/open-hrmp-channel-between-shiden-network-and-sakura-network/3959